We sincerely hope that this guide is helpful for you! Feel free to post any questions or comments that you may have, here or via Discord.
-Sreeper & Gragatrim

From this point on, War Machines will be referred to as WM(s).

WMs are unlocked as a part of the WM Campaign at character lvl 50. WMs are used for completing campaign missions and for competing in the Arena of Kings (level 80).

When unlocking a WM, remember placing a crew into it. Town -> Engineer -> Engineer -> Active squad (swords) -> Edit -> Pencil.

When upgrading Blueprints , jewels or artifacts, focus on Damage and Health , they both generally benefit you a lot. This is however not the case for Armor which basically does nothing for the campaign and should only be upgraded to reach power requirements - For Arena, Armor is fine.

WMs need components (Screws , Cogs and Metal ) and Expedition Tokens for upgrades. Components are unique to each WM, meaning that Cloudfist cannot use the same screws as Talos for example.

Components are obtained by opening Jewel Chests. There are currently 6 different ones available: Wooden , Iron , Golden , Diamond , Opal and Emerald . They all give certain amounts of components, conduits and jewels. The last 3 also give you a chance at getting seals to upgrade your jewels.

The WMs have a catch-up mechanic, which means that a newly acquired WM will get the vast majority of new components until it can THEORETICALLY be lvl’d as high as your highest lvl WM (Meaning that it needs to have the components to do it, but you don't actually have to lvl it). When you have 6+ WMs, you can select 5 favourites. Once your 5 favourites have equal theoretical lvls available, the catch-up mechanic will no longer be in effect.

Conduits consist of Chaos Turbines , Energy Cores and Mana Reactors - A set of resources collected from Jewel Chests. As you collect a certain amount of each, they automatically unlock new WMs for you (Amounts shown in the following section). On average you will earn 1 conduit per 80,6 components earned from Jewel Chests. The drop rate is affected by pooled randomness[firestone-idle-rpg.fandom.com], so the average is guaranteed.

There are 4 types of WMs: Single Damage Dealer (Single-DD), Tank, Multi Damage Dealer (Multi-DD - Also referred to as AoE), Healer

Initially you’re provided with a Single-DD War Machine. As you open Jewel chests, you will obtain Conduits, after obtaining a specific amount, you will receive a new WM.

Below you can see the conduits required and the WM type you will receive:


You can see a list of all WMs here: War Machines - Firestone Wiki [firestone-idle-rpg.fandom.com]

Spend Emblems of Valor on the best Jewel Chests you can (Golden , then Diamond ). It can be tempting to save Emblems of Valor before reaching Campaign Star 100, but it is usually not worth it.

You can purchase the following Jewel Chests from the Exotic Merchant after player lvl 65:


Golden Chest vs. Diamond Chest purchasing
The keen eyed might notice that Golden Chests provide a better value component wise, but keep in mind that this means missing out on epic jewels, legendary jewel seals and lots of ethereal shards. As long as you're missing epic and/or legendary seals, buy Diamond Chests . The additional parts are not worth the considerable loss in equipment.

There are other optimal cases, but what has been mentioned will be optimal for the vast majority of scenarios.

Rarity is an upgrade for your WMs that costs Tools , which can be claimed for free every 6 hours from the Engineer or bought from the Guild Shop.
(The Tool amount received is 225+(engineer lvl*25)
Rarity upgrades cost an amount of Tools and require your WM to be at at a certain minimum lvl. See costs and requirements below.

Rarity upgrades provide an amazing boost to your WM squad as they provide a considerable multiplicative boosts to the whole squad and an even larger boost to the WM itself. Specifically they provide the following bonuses per lvl:
5% increase to the main attributes of the WM itself
5% increase to the main attributes of ALL WMs
5% increase to the main attributes of ALL WMs in the arena
3% increase to the ability chance of the WM itself

Before spending anything make sure to figure out which strategy you want to follow, in the Strategy sections further down in this guide. Refer to your chosen WM strategy, before spending any Expedition Tokens

As a F2P you will most likely never have any spare Expedition Tokens after lvl'ing WMs.
As a P2W or if you somehow do happen to have excess Expedition Tokens , you can either spend them on Tools for an immediate power boost (read the about Tools at the bottom of this section first), or buy Jewel Chests until you unlock Emerald Chests , after that point only buy Elixir of Life . Buying lvls in the PTree is also a possibility, but apart from buying the first few lvls in Battle Cry, Gold, Prestigious and Firestone Effect, it is not recommended AT ALL as you should focus on at reaching Campaign Star 190 to get Emerald Chests , before focusing Expedition Tokens on anything Non-WM related - Even after that point, the PTree does not offer great value.

When buying Jewel Chests, always pick the best Jewel Chests you can EXCEPT Opal Chests - NEVER buy Opal Chests with Expedition Tokens as it’s cheaper to buy Diamond Chests and then Transmute them to Opal Chests .

Purchasing Tools with Expedition Tokens is a consideration for many, early on. Rarity upgrades provide a considerable boost for your WMs and the early rarities have amazing value. However it is worth considering that you will be earning free Tools faster than you can spend them in the long run. Your Expedition Tokens simply cannot keep up with the steep WM lvl requirements for the later rarities.

Early on in the game, transmutation is not worth it, but later it becomes very good. As a F2P you will only be transmuting by using the naturally acquired resources.
When you’ve unlocked Opal chests , start transmuting Diamond chests > Opal chests
When you’ve unlocked Emerald chests , start transmuting Opal chests > Emerald chests
If you’re a big spender, transmuting Diamond chests > Opal chests > Emerald chests is very good, but does require a $100 blimp each week to fuel.

For calculations of possible stars with your current setup use: Grag's Crew Picker tool [crius.feralhosting.com]

For quick required part calculation use: Grag's Simple Part calculator [crius.feralhosting.com]

For calculations of possible stars with your current setup(simple, only need WM power) use: Grag's Simple Campaign Star tool [crius.feralhosting.com]

Preface

All strategies have been determined from data gathered over more than a million simulations via Gragatrim's tool, to determine WM effectiveness in different scenarios.

DISCLAIMER: These strategies are optimal ways to play, but this does not neccessarily mean the most fun for YOU. Don't attempt a strategy that will make you burn out of the game, otherwise this is all pointless. Some strategies involve ignoring certain game aspects and occassionally not upgrading WMs for some periods of time.

Refer to the other Strategy sections for more in-depth information about which WMs to focus on and what to upgrade etc. depending on whether your focus is Campaign or Arena

Credit to Yakinthos for testing this idea.

TL;DR AT THE BOTTOM

By strategically timing when to open Jewel chests (For WM parts) it's possible to save a handful of days on the Campaign Star 40 push. Basically the trick is to open 50 chests just before unlocking a new WM. This will distribute all the parts across your existing WMs and then it'll unlock your new WM. With this method, your existing WMs will get a lot of parts that otherwise would've gone to the new WM. You can then lvl your main(s) to be able to push more missions and thereby get more rewards faster. We will be repeating this "trick" 3 times.

Go to the part that matches the amount of WMs you have

3 WMs
After getting your 3rd WM only open Wooden Chests and save any Iron Chests or Golden Chests for later.
When getting close to unlocking your 4th WM, carefully open Wooden Chests until you're on the verge of the new unlock (only missing 1 conduit if possible). Now open all 50 Iron Chests at once. Upgrade your main(s) as much as possible and push WM missions.

4 WMs
Repeat the previous step, but this time open 50 Golden Chests right before getting your 5th WM. Upgrade your main(s) as much as possible and push WM missions.

5 WMs
Once again, repeat the previous step, but this time with 50 Iron Chests again. You should now be able to push to Campaign Star 40.

--

Remember to spend Emblems of Valor at the Erotic Merchant after reaching lvl 65.

In Yakinthos' tests he was able to get Campaign Star 40 in 14 days with the strategy (F2P starting from lvl 1 on a new server) compared to 19 days WITHOUT the strategy (F2P starting from lvl 1 on a new server)

TL;DR:
Open only Wooden Chests until right before you unlock the 4th WM, then open 50 Iron Chests , do the same before the 5th WM but with 50 Golden Chests and then do the same before the 6th WM but with 50 Iron Chests again. After each opening, upgrade main(s) and push campaign missions.

The strategy for those that want to focus their efforts on increasing their campaign capabilities. This strategy maximises your campaign stars while still allowing a decent arena team

TL;DR below.

The most efficient way to climb the campaign is to primarily lvl a single WM which will carry you through the missions. Campaign can be done efficiently with most WMs. Which one you use does not make a huge difference in the long run.
To help you select your main WM they're ordered by strength here (AGAIN please note that there is NOT a big difference between them - Top to bottom only requires an additional 7 lvls to hit star 190): Thunderclap > Cloudfist > Talos, Aegis, Earthshatterer, Judgement, Harvester > Firecracker > Fortress, Goliath > Curator > Hunter, Sentinel

Now it's time to select your main WM and favourites. We recommend deciding which you will use as your main and which will fill the 4 remaining favourite spots on your team, just after receiving WM #6. After that point, the component penalty for switching favourites or main becomes too large to be worth it, as it will slow down your campaign progress.

Once you've picked your main WM, be sure to be nice to it.. You will be sticking together for the rest of your Firestone journey.

Whenever you have components available for your main, make sure to lvl it. With any spare Expedition Tokens we will be pushing your other WM lvls and rarity, starting with your favourites.
Lvl your favourites with the goal of getting their rarity upgraded. Once your favourites have reached the lvl requirement for a rarity, lvl your non-favourites instead until they're all eligible for a rarity upgrade. After that start lvl'ing favourites to the next lvl required for rarity. (Refer to the Rarity section for lvl thresholds and Tool costs) While doing all this NEVER stop lvl'ing your main. When you have the Tools available for a rarity increase, use it on WMs in this order: Main -> Favourites -> Non-Favourites -> Repeat

For Blueprints, Hero Gear and Artifacts, focus on lvl'ing Damage first, then Health, for your main WM. If your main WM is a DD, use as many dps heroes as possible for it as they increase damage - If it is a Tank, use as many Healer heroes as possible.
You can use Grag's Crew Picker [crius.feralhosting.com] to calculate which heroes are best to use for you.
Armor does does not make a big difference, but does provide a power lvl boost (Spending Blueprints on Armor is recommended on your main WM)
Excess blueprints should be spent in one of two ways:
1. Boost your arena capabilities by boosting dmg, health and armor on all favourites.
2. Boost the non-WM part of the game by boosting WMs depending on their milestone effects, with the following prioritization: Prestige Firestone Gain, Gold, All Attributes

TL;DR

• Pick main WM (ALWAYS lvl it)
  
• On main focus dmg and then health boosts (Blueprints, Gear, Artifacts) + Armor w. Blueprints
  
• Lvl other WMs to be rarity eligible
  
• Lvl rarity on main -> favourite -> non-favourite -> repeat prev. step and this

The strategy for those that want to focus their efforts on increasing their Arena capabilities. This strategy maximises your Arena team while severely halting your campaign progress. The investment required to be competitive in Arena will never pay off.

DISCLAIMER: Focusing on Arena (With the goal of being competitive) is not possible without a considerable amount of spending.

TL;DR below.

To be efficient in Arena we will attempt to create the strongest team possible. Since WMs are random, you will initially have to pick the best of what you get (You can swap them out later). You can refer to the following tier list to help you decide:

WM Tier list for Arena
Preferably use a "balanced" team with either 2 Tanks and 3 Single-DD or 2 Tanks, 2 Single-DD and a Multi-DD (These 2 setups will perform within 1% of each other, as long as tier 1 and tier 2 WMs are used)

Tier 1

• Goliath
  
• Cloudfist
  
• Talos
  
• Fortress / Earthshatterer (Almost equal in power - Preferably use one of them as a secondary tank with Goliath, if you don't have Goliath, they can be used together instead.)

Tier 2

• Aegis
  
• Firecracker
  
• Thunderclap
  
• Judgement

Tier 3

• Harvester

Tier 4

• Hunter
  
• Sentinel
  
• Curator

Initially lvl your favourites equally and push rarity as fast as you can. As you get more WMs lvl them up as well to hit the rarity thresholds. If you get new WMs that are better than your current favourites, feel free to add them to your favourites and start lvl'ing them quickly. Nothing will be wasted as you will still be getting the rarity boosts. The first rarities provide very big power boosts without costing too much (The mechanical fury boost of each rarity upgrade is a massive boost as it provides a 5% boost to all WM stats in Arena added multiplicatively AFTER the rest of the power is calculated)

For Blueprints, Hero Gear and Artifacts, you will want to upgrade EVERYTHING as all stats are relevant for arena.

TL;DR

• Pick a main WM team and make them favourites
  
• Lvl your favourites equally
  
• Upgrade all blueprints, hero gear and artifacts. Focus on favourites first.
  
• Lvl rarity on favourites
  
• Lvl other WMs to be rarity eligible
  
• Lvl rarity on favourites -> non-favourites -> repeat from step 2