I guess everyone knows how Grims and Tomes works but I will explain it just in case.

In each level, you can find 3 Tomes and 2 Grimoires (Grims), increase the quality of your end-of-mission loot box.

Tomes takes the healing item slot of a player, which means he can't carry a healing draught or bandages while carrying a Tome, but he can still grab healing if he finds some and drop the tome.

Grims takes the potion slot of a player, which means he can't carry speed, concentration or strength potions while carrying a Grim. Additionally, if the player drop the Grim he's carrying or dies, the Grim is destroyed and lost for ever. Each Grim the team is carrying will also reduce the maximum health of all players by 30%, but can be reduced with Curse Resistance.

By the end of the day, who takes the Grims and Tomes doesn't matter in a good team, even on Legend. However, some teams might need to organize themselves to guarantee the best survival chances when carrying Tomes and Grims. Making sure the Grim carriers have the lowest chances to die and the Tome carriers not influencing the team's needs of healing can increase survival and success chances dramatically.

Do note that it doesn't matter on bad teams either as they will fail anyway.

I will, for both Tomes and Grims, post a priority list for each of them, then explain the in-depth reasoning behind it for the ones that wants to understand it.

I'm sure the majority of you are here for this so I will start by it. Also, the Tomes carrying priority kind of depends on Grims carrying priority.

The player carrying the Grim should have the lowest possible chance to die. It might highly vary from player to player, but if you see someone that keeps on getting down over and over again but the career he plays is on top of the list, it might better to have someone else carry it anyway.

The second parameter to consider when picking your Grim carriers is how useful potions are on them, since they won't be able to carry one without destroying the Grim. Generally, careers about killing bosses will be really low on the list because of this.

• 150hp careers
  
  • Iron Breaker
    
  • Unchained
    
  • Zealot
    
  • Footknight
• 125hp careers
  
  • Handmaiden
    
  • Mercenary
• 100hp careers
  
  • Slayer
    
  • Battle Wizard
    
  • Ranger Veteran
    
  • Witch Hunter
    
  • Waystalker
    
  • Bounty Hunter
    
  • Huntsman
    
  • Shade
    
  • Pyromancer

• 150hp careers
  Not only 150hp is the highest base health pool that can be achieved, but these carriers are also considered tanks. They have additional ways to extend their survivability and tends to not be as effective as other carriers with potions. I do want to point out that, if your team have more than 2 150hp heroes, that it doesn't really matter which one of these carry the Grims. Some are more effective than others yes, but the difference is negligible.
  
  • Iron Breaker
    Iron Breaker is considered THE Tank of the game. High damage resistance, ignore damage on a regular basis. Even his active is about tanking. If there's a member in the team that will die last, there's a high chance it's the Iron Breaker. This guy is your number one Grim carrier, and will generally always have one with him.
    
  • Unchained
    Despite being closer to a bruiser than an actual tank, the nearly-permanent 50% damage reduction shouldn't be ignored, and a good Unchained will either have good overheat discipline and/or know when to use their active. There's also some builds that are around having as much health as possible.
    
  • Zealot
    Even if he only have a couple of talents to reduce his damages taken, the Zealot have other tools to increase his survivability. His active can not only be used to rush into the fight, but also away to safety, increasing his survival. There's also at least one build centred around maxing out temporary health, which is an excellent survival tool.
    
  • Footknight
    Some might be surprised to see the Footknight this low but let me explain. Yes, he is a good tank, and he might be better than the others above, but he is a victim of his own success. He got a damage reduction aura that also reduce damage taken by other players, which means the other 150hp carriers are even more tankier and so increasing their survivability even more. Additionally, a Footknight with a concentration potion can be truly helping when facing bosses. Due to this, he can even be put lower in this list if your team lack good Boss killers, especially on levels with Lords, like War Camp and Into the Nest.

• 125hp careers
  When you have too many Grims but not enough 150hp carriers, you can fall back on the 125hp ones. They also have good ways to survive so don't expect to lose too many Grims to them.
  
  • Handmaiden
    I actually struggled a bit to know which one to put above the other, but Handmaiden wins because she has a better active to help her survive, despite her better use of potions. She is the Clutch Queen. When she survives, she SURVIVES. Her active allows her to go out of tricky situations and she have good personal survival skills.
    
  • Mercenary
    Mercenary is all about temporary health. And it does help with staying alive. He have some way to reduce damage taken but not every Mercenary use those. Even there, he's a really tanky career
• 100hp careers
  And when everything fails, you got all that's left. Some might argue that grabbing Grims if you don't have 125-to-150hp careers is really dangerous as you go on higher difficulties. It's up to you and your team to see if you get to the point where 100hp careers take a Grim or not. Additionally, some 100hp careers can really make good use of potions (especially against bosses), it is one of the biggest reasons why some careers are above/below others.
  
  • Slayer
    The Slayer is THE tankiest melee career. He got multiple talents to increase his survivability and, even if the players doesn't pick any of these talents, his active allows him to get out of tricky situations (and even have talents to increase his survivability when using it). You can almost put a Slayer on par with 125hp careers.
    
  • Battle Wizard
    Even if her effectiveness can be debated, the survival tools the Battle Wizard have cannot be ignored. An active that allows her to get out of fight easily and the ability to reach 100% block cost reduction are powerful tools for a Grim carrier.
    
  • Ranger Veteran
    Funny how Bardin is overall high in this list, isn't it ? The Ranger Veteran, even if he lacks any form of tankiness, the Veteran Ranger can make good use of his active ability. Even if it's not a massive survival tool, it is still an efficient one. Additionally, the Ranger Veteran tends to have problems making good use of potions.
    
  • Witch Hunter
    Now we start to reach careers that severely lacks survival tools. The Witch Hunter only have no stamina cost against frontal light attacks and an AoE active with a big cooldown. He also have some talents that increse his dodge range/stamina/temporary health per taggable target killed, which helps with his, and even his team, surivival. He's more of a support career and can't do much with potions.
    
  • Waystalker
    Both a bit below the Witch Hunter and a bit above the Bounty Hunter is the Waystalker. Even if she have health regeneration until she reach half health, the actual health she will recover will be reduced the more Grims your team have. She can also do wonders with potions. Honestly, I don't know if she should be below or above Bounty Hunter.
    
  • Bounty Hunter
    The Bounty Hunter is pretty similar to the Witch Hunter, but with even fewer ways to keep himself alive. However, he can profit a bit more from potions. For a Grim carrier however, this is a bad thing.
    
  • Huntsman
    It is true that the Huntsman's active makes him invisible, but he mostly use this to take down important targets or bosses. He also profits a LOT from any potion when facing bosses too, making him an even worst Grim carrier.
    
  • Shade
    The Shade have all the problems of the Huntsman but she's also melee-focused, putting her in danger rather commonly. In short, you should never, ever, have a Shade carrying a Grim.
    
  • Pyromancer
    And at the bottom of the list is the Pyromancer. No survival tools, an active that is all about dealing damage AND can abuse potions like a maniac, she is the worst possible Grim carrier. If you are a Pyromancer rushing to carry Grims, you should seriously reconsider your choices in life.

This one is a little bit tricky. Since you can have up to 3 Tomes in the team, the idea is to have the player not carrying one to use healing items as best as possible. This means that it will barely depends on the career, and much more on the Necklace Trait.

Necklace Traits are about healing and healing items. There's only four*, so it will be rather easy to make a priority list of them. But how do you know which trait your teammates are using ? You can't ask them every single game what they use, and the only one telling the team what they use are either Natural Bond or Hand of Shallya's users.

You will see why in the list, but knowing about those two traits are more than enough to know who will be the first(s) to carry Tomes and who will never touch them. As for the other two Necklace Traits, you will learn who use these with experience and depending on their career and overall build.

And an important note before we go to the priority list : if you are the player not carrying a Tome, grab bandages ! Your teammates can't heal themselves unless you find healing items and you can't give your Healing Draught if they go down ! Have bandages to be able to heal them !

• Natural Bond (Grants passive health regeneration but can no longer heal yourself)
  
• Shallya's Boon (Increases effect of healing on you by 30%​)
  
• Grim's priority list
  
• Healer's Touch (25% chance to not consume healing item on use)
  
• Hand of Shallya (Healing an ally with a medpack also heals you for 35% of your missing health)

• Natural Bond
  Pretty obvious Tome carrier. Since he cannot profit from healing items and depends on his teammates to reset his wounds (downs), Natural Bond users are the best Tome carriers you can have. If you have one of these players in your team, make sure he is the first one to have a Tome. This is mostly used by 150hp careers, especially Ironbreaker or Unchained. Some Waystalkers might use this but, even if their use is debatable, are still good Tome carriers.
  
• Shallya's Boon
  Players using this Trait mostly use it to increase the amount of health gained from crits/kills. It does not truly increase the healing abilities of the user, and does not help at all resetting more downs. This is mostly used by 150 careers and builds which exploit temporary health.
  
• Grim's priority list
  When no one have any Necklace Traits, it's better to go back to the basics : who have the lowest chance to go down and need to use healing items ? I use the Grim's as a shortcut, but it's still something like 150hp careers -> 125hp careers -> 100hp careers. This is mostly a situation you will see on lower difficulties, since not everyone might have found Orange items at all.
  
• Healer's Touch
  Even if it's not better than 100% chance to heal two teammates, you can however potentially increase the number of wounds removed. This trait is mostly common on 125hp-100hp careers.
  
• Hand of Shallya
  This Trait is about healing your teammates. If you carry a Tome, you simply cannot profit from this trait unless you find bandages along the way. Additionally, having a 100% chance to heal 2 persons is better than 25%. Even if it can be argued that it's not as useful since bandages remove wounds for the healed and the healer, having two players with their downs reset AND with more health is not to be ignored. This trait is generally used on careers with increased healing talents (Mercenary, Ranger Veteran and Battle Wizard).

*Players using Barkskin (Reduces damage taken by 50% for 10 seconds after using healing supplies) can pretty much be considered as players without Necklace Trait. They can have a lower priority compared to players without Necklace Traits but the difference is so negligible you can ignore it.

Don't hesitate to voice your opinion in the comments : the more opinions and experience I gather, the better this list will be.

Also, don't hesitate to share this guide if you feel that someone wants and/or needs to learn about Tome and Grim priority.

I thank you for reading, and have a nice day.