Beat the main campaign and expansions on Hardcore Rules or higher

First thing you should do before starting any of the campaigns is to make sure you set your difficulty to either 'D&D Hardcore Rules' or 'Very Difficult' in the options menu. You will need to beat the official campaign and expansion packs—without lowering the difficulty setting—for this achievement to unlock.

Note: It appears that you cannot lower the difficulty at any time during your gameplay without voiding this achievement. Please comment if you find out otherwise.


Win all events at the West Harbor Harvest Fair

This achievement is obtained by winning all the events during the prologue/tutorial mission that occurs before Act I. These quests include: The Harvest Brawl, The Tourney of Talent, The Archery Competition, and The Knaves' Challenge. The latter quest involves obtaining three different coloured feathers by disarming an electric trap set on a pile of logs, unlocking a nearby chest, and pick pocketing the man wearing green near Georg Redfell.


Help someone who doesn't deserve it

During the attack on West Harbour at the start of the game in Act I—make sure to heal Ward Mossfeld yourself—or with the aid of Brother Merring.


Choose a Prestiege Class

Note: That's the game's typo, not mine. It should read as Choose a Prestige Class
Make sure to read through all the prerequisites needed for the (locked out) classes to ensure that you're contributing towards a character build that can choose to acquire a prestige class later in the game. Pay attention to these prerequisites each time you level up your character.
Mask of the Betrayer provides instant access to level 18 at the start of the game, so alternatively you can do a character build with a prestige class in that expansion pack instead.


Become one of the Neverwinter Nine

When Lord Nasher invites you to become one of the Neverwinter Nine at the start of Act III, make sure to accept his offer and this achievement will unlock.


Reach level 20 for any character

Earn enough XP to reach level 20 during Act III of the Official Campaign.
Alternatively, playing Mask of the Betrayer will grant one's character level 18 at the start—which makes reaching level 20 doable in the early game.


Take a rest in the final dungeon

In the final dungeon (Vale of Merdelain)—click the Rest icon and rest for 5 seconds (without being interrupted by one of the random encounters that spawn when resting in this dungeon).


Complete Neverwinter Nights 2

This achievement unlocks when you complete the Official Campaign for NVN2.

Complete Khelgar Ironfist's quest line

Recruit Khelgar at the Weeping Willow Inn (this happens very early on in Act I) and complete his companion quests. After visiting the Temple of Tyr located at Neverwinter's Merchant Quarter—talk to Prior Hlam—he will assign you 3 separate quests: the Trial of the Even-Handed, the Trial of the Maimed, and the Trial of Justice. You will need to complete these three quests/trials to finish the Khelgar Vision Quest and unlock this achievement.

• The Trial of the Even-Handed requires you to raise your influence with Khelgar—talk to him—and then select the dialogue option "I wanted to ask you about some of our companions." If your influence is high enough with Khelgar you will be successful in your influence check. After this influence success—talk to Prior Hlam to finish this trial/quest.
  
• The Trial of the Maimed requires you to go to the Dwarven Scouts area after visiting Old Owl Well. Finish this scouting mission by acquiring the Gauntlets of Ironfist in the cave area (do not sell or discard these gauntlets at any point—they are needed in Act III for the quest Alliance with Clan Ironfist). Don't forget to grab the Strange Part in the cave upon entering, you will need this item to access the final area in the cave to finish the quest. After completing the trial, talk to Prior Hlam to finish this quest.
  
• The Trial of Justice requires you to complete the Ember trial in Act II. The Trial of Justice completes itself automatically when Khelgar speaks of the Ember trial before the fight against Lorne. Now you can talk to Prior Hlam about having completed this trial—thus ending the quest. Additionally, Khelgar can now become a monk.

Complete Neeshka's quest line

Recruit Neeshka at Fort Locke (this happens very early on in Act I) and complete her companion quests. In Neverwinter's Docks District, you will be attacked by Bennon, and when you enter the Merchant Quarter you will be attacked by Tremmel. After these two attacks, travel to the Moonstone Mask and talk to Ophala to uncover Leldon's Hideout located in the Merchant Quarter. Retrieve Leldon's Lucky Coin and fight Leldon—who subsequently uses smoke bombs after the fight is over in order to retreat.
In the beginning of Act II, leave the Sunken Flagon with Neeshka to encounter Tasha. Afterwards, travel to Neverwinter's Blacklake and go to the Collector's Mansion. In the kitchen area, acquire the Empty Bottle from the Wash Basin and drag the item into the Vase of Water next to it to make a Bottle of Water. You will need this to acquire a key on the second floor level at the fireplace. You will also need to acquire Vania's Key from Vania (first floor level) and the Collector's Key from the Collector (second floor level). The Collector's door requires the Collector's key, the key from the fireplace and the code '513'. Open this door—defeat Leldon when he arrives—after defeating Leldon a cutscene occurs with Neeshka and you unlock this achievement.


Complete Elanee's quest line

Recruit Elanee at the Road to Highcliff (this happens very early on in Act I) and complete her companion quests. In the Neverwinter Docks District, you will find a Wounded Wolf very close to the Weaponsmith (marked on the map) in an alleyway. Talk to the Wounded Wolf so that you can then travel to Skymirror and converse with the Elders of the Circle of Swords.
In Skymirror, you will need to cast 4 separate Level 2 Nature spells on the Old Worn Trees marked on the map. Open Elanee's spellbook and equip Bull's Strength, Cat's Grace, Creeping Cold and Owl's Wisdom. In that same order, cast the spells on 1st, 2nd, 3rd, and 4th trees, interacting with the tree each time after casting the spell. Now you can talk to Naevan at the lake.
You will have to wait for the start of Act III where you can then travel to the Circle of the Mere and complete Elanee's companion quest. Make sure you garner enough positive influence with her to keep her on your side when you come up against the Circle.


Complete Qara's quest line

Recruit Qara outside of the Sunken Flagon in Neverwinter's Dock District during Act I and complete her companion quests. In Act III, talk to Khralver Irlingstar in the Crossroad Keep Courtyard and tell him that you have accepted Sydney Natale's offer to go on a journey to Neverwinter with Qara and Zhjaeve. Before arriving at the agreed upon location—you will encounter Sydney in a Forest. Deal with this encounter and the achievement will unlock.


Complete Grobnar Gnomehands' quest line

Recruit Grobnar at Neverwinter Wood during your travel to Old Owl Well in Act I and complete his companion quests. You will need to acquire 3 separate items to reactivate the Construct: a Vial of Glowstone Water, The Ancient Art of Golemcraft, and a Rune-inscribed Iron Piece.

• For the first item—travel to the Glowstone Cave (via Duskwood or Ember) and make sure to have Grobnar in your party. After collecting the Glowstone item, move towards the lake close by and you will acquire a Vial of Glowstone Water.
  
• For the second item—travel to the Crossroad Keep Interior's Library section. The Library contains Aldanon's Bookcase, which will have The Ancient Art of Golemcraft book.
  
• For the third item—travel to the Gem Mines and acquire the Rune-inscribed Iron Piece from the Cauldron in the room that possesses two workbenches.

After acquiring all three items, you are now ready to speak with Grobnar in regards to reactivating the Construct.


Upgrade Construct to the maximum

After completing the Reconstruction achievement—talk to Construct and use the skills Craft Armour, Craft Weapon, and Craft Alchemy to upgrade him. Have Sand in your party while talking to Construct if you do not have sufficient points in Craft Alchemy. If you do not have sufficient points in any of these skills—try using equipment and spells to enhance your Intelligence attribute.


Have a close relationship with a companion

If your character is male—you will need to gain high influence with Elanee.
If your character is female—you will need to gain high influence with Casavir.
Once this prerequisite is accomplished—during Act III there will be a cutscene on the wall of Crossroad Keep—where either Elanee or Casavir declare their love to your character. Reciprocate to unlock this achievement.

Alternatively, this achievement can also be unlocked in Mask of the Betrayer.
If your character is male—you will need to gain high influence with Safiya.
If your character is female—you will need to gain high influence with Gann.
Once this prerequisite is accomplished—at the end of Act II—while you are entering the Gate of the Betrayer, either Safiya or Gann declare their love to your character. Reciprocate to unlock this achievement.

Complete the City Watch of Neverwinter quests

When you dock at Neverwinter for the first time during Act I, you have the option between joining the City Watch or the crime syndicate in Neverwinter. To unlock this achievement—join the City Watch and complete all of their quests. This achievement unlocks when you complete the final quest—Protecting the Watch's Informant.


Complete the Thieves of Neverwinter quests

When you dock at Neverwinter for the first time during Act I, you have the option between joining the City Watch or the crime syndicate in Neverwinter. To unlock this achievement—join the crime syndicate and complete all of their quests. This achievement unlocks when you complete the final quest—The Informant Uncovered.


Obtain the Golden Lute of Shazar in a honest competition

At the start of Act II, travel to Neverwinter's Blacklake. Move towards the stadium close by and challenge the lutist Cain Lethellon. For round one, pluck the strings in this order: '44124754'. For round two: '234451122'. For round three: '2332233175' and for the final round: '35345272725'. Make sure to use any skill checks that you are high in throughout the competition to gain an edge. Use Sand to heckle Cain, this will give you +1 influence with Sand and thus will be helpful for the Not Guilty achievement later on. After defeating Cain—you can now obtain the Golden Lute of Shazar.


Prove your innocence at the Trial

During Act II, you will have to vindicate yourself of the charges laid before you at the Trial for the Ember massacre. To unlock this achievement you need to reach a verdict in your favour at the Trial. Here is a list of things to focus on in order to succeed with the Ember trial:

• During your first visit to Ember in Act I, allow Marcus to take the skinning knife from Bishop.
  
• In Act II, talk with Nya in Port Llast and finish the assigned quest by revisiting Ember and using the Bag of Wyrmsage on all of the corpses. Ember also has the Quartermaster's Log and the Poisoned Corpse that prove as useful evidence.
  
• During the revisitation of Ember, make sure to go inside the Well and speak to Marcus. You can now gain his favour as a witness for the trial.
  
• Traverse further inside the Well to acquire the Signet Ring and Glowstone in the Caverns.
  
• At Duskwood—acquire the Alteration Powder from Lyssa.
  
• Optionally—you can also choose to use Alaine when you talk to her in Port Llast as a witness for the trial. Although as long as your influence is high with Shandra—this decision appears to hold little weight.
  
• Gain a higher positive influence with Sand and Shandra.
  
• Increase stats like diplomacy, bluff, intimidation, lore, intelligence, and charisma for enhanced dialogue options. You can buy a Nymph Cloak +4 and an Amulet of the Master from Dayne Lynneth in Blacklake. The cloak provides +4 Charisma and the latter provides +6 Diplomacy and +6 Lore. Headgear is discarded during the trial and will be of no assistance.

If you achieve enough successes during the Trial—the achievement will unlock while Lord Nasher is declaring your innocence.


Fully upgrade your Keep

Talk to Master Veedle in Crossroad Keep Courtyard and pay for all of the available upgrades using the Keep's funds and/or your own gold. Every time you command Veedle to upgrade the Keep and its surrounding area—travel away from the Courtyard and revisit it to reset Veedle for another upgrade command to be commenced. You will have to wait until Act III to repair the tower and church. Ordering all of the Keep upgrades via Veedle will unlock the achievement.


Defeat the King of Shadows

During the endgame in Act III, choose to fight the King of Shadows and defeat him.


Join the King of Shadows

During the endgame in Act III, choose to join the King of Shadows and defeat your companions.

Use Suppress to reduce craving with five spirits nearby

During Act II or Act III—cast the Spirit-eater Feat Suppress while there are at least five spirits within your 20m radius. I unlocked this achievement by casting Suppress on a friendly Telthor (Spirit) while it was roaming with its group in the south-west of the Ashenwood area. Ashenwood and the Nightshore—which are both filled with spirits—makes for an ideal location to get this achievement.


Reach level 30!

This is only really doable in Mask of the Betrayer—or any other expansion pack—that allows the player to get to level 30.


Complete Mask of the Betrayer

Finish the Mask of the Betrayer expansion pack to unlock this achievement.


Devour Okku's spirit

Towards the end of Act I—you will have the choice to either resist the temptation to devour Okku's spirit or devour Okku's spirit. Choose the latter option for this achievement to unlock.


Side with the Crusade

At the start of Act III—during the parley outside the Supplicants' Gate—side with the Crusade and this achievement will unlock.


Side with the City of Judgment

At the start of Act III—during the parley outside the Supplicants' Gate—side against the Crusade and this achievement will unlock.


Make Akachi remember who he was

This requires completing the good / neutral ending for the game. During Act III—at the end of the game in the Soul area—choose to use the Mask of the Betrayer and reunite Akachi with his past.


Kill Akachi

This requires completing the neutral / evil / selfish ending for the game. During Act III—at the end of the game in the Soul area—choose to slay Akachi.


Devour Akachi's spirit

This requires completing the evil / selfish ending for the game. To unlock this option, you will need to acquire Myrkul's Essence by devouring Myrkul's spirit at the end of Act II in the Boneyard. During Act III, after performing this prerequisite—and before you use the portal to enter the Soul area—you will now get the option to tell the Red Woman that you "devoured the essence of a god..." and that you can master the hunger. When you defeat Akachi—make sure to choose the third option to "devour the Faceless Man... gorging upon his ruined soul"—and unlocking this achievement.

Establish a trade route from each city

During the start of Act II, you will acquire the means to start up Trading Posts and construct Caravans in the Sword Coast. I recommend going for this achievement (or Expert Merchant) first—for it delivers a very big bonus for the accumulation of your Trade Bars—which will be invaluable for unlocking the Honest Work and the Good Company achievements. To unlock this achievement, start up a Trading Post and Caravan(s) with Neverwinter, Leilon, Conyberry, New Leaf, Highcliff, Phandalin, Thundertree, Port Llast, and West Habour. Neverwinter, Port Llast, and West Habour require the completion of particular quests before you can establish Trading Posts in these three areas.
Make sure to visit your Merchant Headquarters in Crossroad Keep periodically to speak to Variel for obtaining your share of the Trade Bars that the merchant company actively accumulates. The more Caravans you construct—the more Trade Bars your character will receive.


Get all the merchant company and caravan upgrades at Crossroad Keep

During Act II, visit the Merchant Headquarters in Crossroad Keep and speak to Variel for 5 separate quests to upgrade the merchant company. Complete these five quests.
Outside the Merchant Headquarters in the Crossroad Keep Courtyard you can speak to Caravan Master O'Dell to construct Caravans for all of the Trading Post locations in the Sword Coast: Neverwinter, Leilon, Conyberry, New Leaf, Highcliff, Phandalin, Thundertree, Port Llast, and West Habour. Neverwinter, Port Llast, and West Habour. You will need to go through and max out the caravan upgrades for all of the Caravans you have constructed—which requires a fair amount of gold to accomplish.


Buy a resource for the lowest price and sell it for the highest

In Act II, you can trade with Phandalin to purchase Skins for 1 Trade Bar (per one) and then trade with Highcliff to sell these Skins for 5 Trade Bars (per one). Doing this unlocks the achievement. There are numerous ways to unlock this achievement, but this is likely the cheapest and simplest.


Reach the directorship in any organization

In Act II, you will need to choose to join one of the three cartels in Neverwinter's Temple of Waukeen. After you progress and essentially complete Act II by finishing its entire main quest line—with the final quest being Conyberry - The Meeting—you will be able to acquire the directorship of the organisation from the cartel representative that you had chosen earlier.


Complete Storm of Zehir

Finish the Storm of Zehir expansion pack to unlock this achievement.

Complete Rinara's quest line


Complete Mantides' quest line


Complete Charissa's quest line


Complete Mysteries of Westgate

Finish the Mysteries of Westgate expansion pack to unlock this achievement.


Become a Champion of the Arena


Complete the Church of Lathander quests


Complete the Ebon Claws quests


Become a vampire

Win all events at the West Harbor Harvest Fair


Upgrade Construct to the maximum


Fully upgrade your Keep


Obtain the Golden Lute of Shazar in a honest competition


Prove your innocence at the Trial


Complete the City Watch of Neverwinter quests


Complete the Thieves of Neverwinter quests


Defeat the King of Shadows


Join the King of Shadows


Devour Okku's spirit


Devour Akachi's spirit


Side with the Crusade


Side with the City of Judgment


Make Akachi remember who he was


Kill Akachi


Become a Champion of the Arena


Complete the Church of Lathander quests


Complete the Ebon Claws quests


Become a vampire

• Quick save (F12 by default) before all interactions/dialogues to ensure you maximise the influence, gold and/or XP that can be gained. Reload if you are unhappy with the direction taken—whether in influence, gold or XP gained—and see if a selecting a different set of options better suits your goals. To enhance your dialogue options throughout the game—invest in stats such as: Charisma, Intelligence, Wisdom, Lore, Diplomacy, Bluff, Intimidation and Taunt.
  
  
• Every time you level up—make a saved game file with the name of that particular level up (e.g. Lvl 1, Lvl 2, &c.)—before making any changes to your level. This will help you later on if you ever decide to retrace your steps to choose a different character build. Additionally, you are more likely to have a saved game that corresponds well with any missed achievements.
  
  
• Keep at least one companion active on your team with a high Strength attribute at all times. This character can serve as your pack mule—very handy for selling items and gaining gold. Additionally, having a Rogue on your team for disabling traps and unlocking chests is a good idea for maximising item & gold gains. Invest in your character's Charisma, Appraise and Lore stats for maximising gold gains when selling to merchants (these stats also help reduce gold prices when buying items from merchants as well).
  
  
• Wipe out all enemies whenever you get the chance to. Every creature slain will contribute towards your total XP and thus make for a higher level during the endgame phase. Note: try to get the final hit on enemies when NPCs (who are not in your party) are attacking enemies. Otherwise, your party may not earn the XP for those kills. There are certain targets that are better dealt with through questing and/or with dialogue, as they provide more XP this way. Kristel (the giant Spider found in the Glowstone Caverns of the Official Campaign) is a good example of this—you will get far less XP by slaying him (a little more than 200 XP) than if you decide to feed him an Insect Collection and let him join your party (1000 XP).
  
  
• Every time you pick up a new quest—especially a side quest—search up a guide online to see how it is completed. Don't leave room for guessing if you have no clue on how to do it, you could be missing out on a fair bit of XP and/or influence with particular companions. Make sure you check your journal periodically throughout your gameplay to remind yourself of which quests need to be completed and handed in.

• Whenever you encounter a new vein of Ore in any of the cavern areas—make sure to click on them—your interaction with a new vein of Ore earns 50 XP each time. There is a total of 16 locations where the veins of Ore can be found throughout Act I, Act II, & Act III.
  
  
• Talk to Retta Starling during Act I after the battle in West Harbour to pick up a quest entitled A Soldier's Story. In Act II—after defeating Lorne in the duel for the Ember trial—travel back to West Harbour and redeem the quest by talking to Retta Starling. This will earn 500 XP.
  
  
• Feed Kristel (the giant Spider found in the Glowstone Caverns) an Insect Collection (which is an item you can pick up after eliminating the two Werewolf Gnomes in Duskwood's cave). After feeding him, let Kristel join your party for a bonus of 1000 XP.
  
  
• After gaining access to Neverwinter City's Blacklake, go into the Church of Lathander to pick up the quest Natrisse's Request from Dawnbringer Natrisse. Travel back to West Harbour and talk to Brother Merring to hand in the quest for 1500 XP.
  
  
• To maximise XP at Riverguard Keep—do not kill the bugbears you encounter for the first time. Instead, allow them to leave. Upon exiting this Keep you will now have a larger mob to wipe out for additional XP.
  
  
• To maximise XP in Riverguard Keep's Second Level—clear out the area of enemies before unleashing Ribsmasher for the 100XP bonus.
  
  
• In Act III—after you have paid Master Veedle to rebuild the church—you can enter into the church and receive a quest called Atonement (this might only apply for evil aligned characters). Complete this quest by slaying the Red Dragon and then return to the priest at the Keep's church for 1000 XP.

• Casting too many spells (especially AOE spells) at once—whether it be your own party or the enemy—may make the game crash more frequently.
  
  
• Major Bug Warning for the Official Campaign
  When you travel to the Ruin of Arvahn for The Statues of Purification quest, make sure you do not enter the Temple of Seasons before interacting with the first Purification Statue located nearby the World Map (i.e. the outside entrance).
  If you enter the Temple of Seasons before performing this interaction with the Purification statue outside, you might end up with a bug that will make you unable to have the needed dialogue cutscene with the Purification Statue inside the Temple of Seasons. If your game gets this bug—you will have to use either a prior save or some other workaround.
  
  
• If anyone encounters any possible bugs and/or things that make the game crash—please comment them and I'll add it to this list. Always better to know about these pitfalls before they transpire.

• During Act I in the Middle Barrow. Bash and destroy the Bear skeleton to unseal the passageway. This quest action will spawn multiple enemies—which helps to maximise your XP gains. This action does, however, shift your alignment to +1 Chaotic.
  
  
• During Act II and beyond—make ample use of the pause button. In-game time diminishes your character's Spirit Energy bar, and this will have numerous adverse consequences.