GrimTools: Battlemage, Level 100 (GD 1.2.1.0) - Grim Dawn Build Calculator
Even though we have very few opportunities to play together as the KotER team, we still enjoy exploring team-based and deep-sr based builds for the lolz of it. Here’s the sort of stress testing I like to put the tanks through in solo play to get an idea of how they might do in a team. 
Damage Reduction: Surviving 1,000,000 Damage
This is one of the best tanks that I’ve made. Keep in mind - This tank is designed for team play. It does no damage, and relies on specific team buffs. But presuming that with team buffs, it’ll have even more HP, and 83% physical resistance, then it has about the best overall damage reduction that I can get. It can probably be tweaked, but… let’s do a cheeky damage calculation based on % values.
Sources of % damage reduction/absorption include:
- 35% Reduced Target’s Damage from War Cry
- 20% DR from Menhir’s Bulwark
- 32% DR from Maiven’s Sphere
- 20% DR from Menhir’s Bastion
- 25% DR from Nature’s Guardian’s
- 83% DR from resistances
Let’s say an enemy can deal 1,000,000 damage to the player in deep SR.
Reduced the damage by 35% from war cry:
- 650,000
Then from here each % damage reduction is based on the previous reduced value (in any order). So we get 20% DR from Menhir’s Bulwark is 650,000 * (1 - 0.2):
- 520,000
32% DR from Maiven’s Sphere is 520,000 * (1 - 0.32):
- 353,000
20% DR from Menhir’s Bastion is 353,000 * (1 - 0.2):
- 282,880
25% DR from Nature’s Guardian is 282,880 * (1 - 0.25):
- 212,160
83% from resists is: 212,160 * (1 - 0.83):
- 36,0067.2
After then, flat damage absorption and armour and so on is applied to reduce the damage further. But even without that, as this build has 43k hp even without team hp buffs, it will survive a 36k hit. Therefore, this build is capable of tanking attacks that pre debuffs/buffs deal 1 million damage.
Healing
Obviously then, even if it takes an attack like this, it couldn’t possibly withstand another follow up attack - it would survive, but only barely. So, the next most important thing is how quickly the build can heal.
Without team buffs, this build has a Healing Increase of 50% and 8000+ regen. In a team, Healing Increased goes up to around 80%, and regen goes up to around 12-15k. Even at only 50% healing effects increased, this build’s Menhir’s Will will heal for 100% of HP when triggered. At 80%, things like Blood of Dreeg will heal for about 68% of this build’s hp. Which at 43k hp is a heal of 29k
Aggro
Finally, to make it an effective tank in a team, it has to be able to hold aggro away from the team. It needs taunts, and lots of 'em. This build isn’t the best taunter, but it’s not bad. It has a lower cooldown War Cry for hitting the masses and catching strays. Then, the Conduit of Warring Whispers necklace gives Blade Arc taunt on hit… so every blade arc hit applies another taunt, and can hit 11 nearby targets with each swipe. That’s pretty good for keeping aggro.
Takeaways
But despite all of this, you know what we’ve learned from making tonnes of incredibly durable deep SR tanks?
Pet builds are still better candidates for the job. 
A single pet build can have like 5 taunting pets with 100k hp, any of which can be resummoned as required. The player can stand back away from the fight without as much concern of death. Pet sets typically boost player HP quite high, so they can still take a hit if they need to. On top of providing a meatwall to take the aggro, pets can also deal incredible damage unlike this tank build. For example - In deep SR, Zantarin’s little minions can one-shot players, and they don’t die particularly quickly - you need to take them down fast, and the only way to prevent them from building up into a zerglike swarm is to make sure the team has enough damage to take them AND Zantarin down quickly.
Finally, if a pet tank dies, the boss’ hp doesn’t reset 
Enjoy~
I’ll check out on the ones you suggested.