support zealot :)
 Zealot Build - Warhammer 40k: Darktide 

entire gimmick of this build is book giving "unkillable" status to yourself and allies, so on a team of zealots that all run holy rev, they can heal to 25% of their health by doing damage whenever in range of active book zealot. holy rev no longer needs until death to proc to activate and activates instead anytime they are given the "unkillable" status. normally, a zealots only way to get "unkillable" is from until death- which is on a 2 min cooldown, from zealous pilgrim- locks you out from taking holy rev, or while casting book- but you cant attack while casting book. if you have a team of zealots all with holy rev, all of them can heal to 25% of their health while "support zealot" casts book.

 additionally, i think book zealots are the one kind of zealot build where taking fire nades is actually maybe more optimal than throwing knives because you can throw a nade, then pop book while your nade in doing damage, healing yourself. can use nades as a self healing tool on this build.     

if i had to say which nodes are "mandatory" for what the build is trying to be- id say; immolation grenades, holy revenant, chorus of spiritual fortitude, scourge (for crit chance), invocation of death, blazing piety, and righteous warrior. these i believe to be the only necessary talents, but given these choices that makes others talents easy picks like punish impiety (due to build not getting much attack speed from other sources like zealot normally gets from either FotF, martyr, IJ), enduring faith, eclassiarchs call, binded by blood, etc. 

weapons and curios dont matter obv, just thought new crusher with skull crusher and thunderous was actually cool as "support" bc special explosion makes all enemies hit by it take additional damage from you and allies from both skullcrusher stagger AND applies brittleness to everything. lethal proximity on the bolt pistol gives a 25% global increase to all explosions, including new crusher special, making even enemies get hit by debuffs. bolt pistol is also a great pairing with no throwing knives :)

I think any weapon could be taken, just flamer might not be so good with no throwing knives, and id seriously take fire nades for self heal during book. i suppose tho you could take throwing knives and a flamer and could get burns stacks on a bunch of stuff then pop book to heal, but i think fire nades are better bc your not just relying on burn stacks for damage but a whole pool of fire on the ground. another cool option I thought off was shock maul, works as a "support" weapon as well as it also has access to skullcrusher and its special its pretty good as a support utility. also, I dont know how much this would do, but using special to electrocute an enemy and then immediately swap to book to heal could do something? same goes potientally for a flesh tearer and uncanny strike combat blade i guess, but i think both these options, while are good weapons, i wouldnt rely on for self heal and wouldnt be as good as fire nades or even the flamer for self heal. 

meow