the fire sunder is pretty much just used to break immunity so Tainteds can do some damage too, right ?

the sunders stats dont really matter that much? not as much as for an Apocalypse-lock

right, although your blood boil has a fire damage component too

For the recommended current build, I use latent flame rift to summon tainted, then swap back to renewed bone break
The only damage I'm scaling is the physical on blood boil. Once tainted are summoned with flame rift its not doing anything besides scaling the fire on blood boil, since the sunder stays locked in on tainted.

We ran through a few pages ago the math on variants. To lay it out again and fix some mistakes, here's three possible builds:

Build A: +blood boil dps, -bind demon dps, max QoL: Uses obsession, shako, 2/20 ammy, enigma, ars baalos, 2x soj, fire sunder, defender's fire and a facet. Has unlimited teleports with no mana pots. Has 20 blood oath, 1 bind demon.
Build B: +bind demon dps, -blood boil dps, max QoL: Uses obsession, shako, 2/20 ammy, enigma, ars baalos, 2x soj, phys sunder, protector's stone and cham. Has unlimited teleports with no mana pots, 20 bind demon, 1 blood oath.
Build C: max blood boil dps, -bind demon dps, min QoL: Uses mang song, 3/20/2 circlet, 2/15+ ammy, enigma, ars baalos, 2x opalvein, fire sunder, defender's fire and 2x facet. Needs to chug mana potions. 20 blood oath, 1 bind demon.

Leaving out 4 skillers, using might merc, the builds wind up as (they all have same tainted power):
(A): 5215 fire / 4535 phys on blood boil with -25% fire pierce and 31.7k jab on a lancer. Has lots of additional resists, life, mana, mf, fhr and teleports for free
(B): 1451 fire / 4535 phys on blood boil with -20% phys pierce and 48.8k jab on a lancer. Has lots of additional resists, life, mana, mf, fhr and teleports for free
(C): 6122 fire / 4535 phys on blood boil with -45% fire pierce and 31.7k jab on a lancer. Glass cannon that will struggle to max resists and uses mana pots to teleport

Now what matters most for blood boil is its damage against fire immunes. You simply don't need it against almost any non-immunes, even including heralds. The DPS is too insignificant compared to tainted/lancer.
It does matter a bit for clearing screens of small chaff enemies like non-immune flayers, where even low damage boil should be sufficient.
And it does matter for speeding up kills on big chonky immunes like arachs, venom lords, etc etc.
The fire-based builds get to pierce those immunes and deal some significant extra damage, but its still not that much contribution compared to the physical. They do far more damage against non-immunes.

So to compare their blood boil damage against a few monster archetypes, assuming amp + conviction active.

0% fr / 0% dr (crow nest) -> A = {19500}, B = {11754}, C = {21314}
25% fr / 25% dr (claw viper) -> A = {17584}, B = {11165}, C = {20180}
50% fr / 33% dr (unraveler) -> A = {15917}, B = {10439}, C = {18593}
100+ fr / 33% dr (doom knight) -> A = {10024}, B = {8480}, C = {11675}
100+ fr / 50% dr (venom lord) -> A = {9254}, B = {7710}, C = {10904}
100+ fr / 100% dr (+stone skin*) ->A = {6986}, B = {9070}, C = {8637}
* currently bugged, amp applies -100%, amp + bone break applies -200%

The most relevant case is monsters like doom knights / venom lords. The phys build is losing about 16% of its blood boil dps vs those immunes, in exchange for 54% higher bind demon dps.
The difference in blood oath impact is pretty negligible, it doesn't scale its % on you by more than a few %, and while you lose 1/3 the demon HP, you can bind a higher HP unique demon and have more HP overall.

I recommend build B: Using just physical damage on blood oath, getting a much higher bind demon DPS
Against the monsters you actually want to use blood boil and it matters how much DPS you do per cast, max blood oath fire-based builds have only a marginal improvement in dps over just using -20% dr and ignoring fire entirely. A mang songs build can kill vampire lords or thorned hulks or serpent maguses faster with blood boil, but what does it matter if they die in 1 hit to tainted? But when you're just telestomping uniques/champions, bind demon damage actually matters. Same with fighting big heralds where bind demons can deal more dps than tainted even vs non-immunes. And against packs of tanky enemies like venom lords, a higher bind demon can matter more than the marginal ~20% higher DPS you can get on blood boil.
And frankly the mang songs build just feels unplayable, the mana usage is crippling

So with all that considered my recommended overall build is;


Runtime gear:
Obsession (in a +3 teleport base, war/rune/archon staff)
Enigma
Shako (cham)
+2/20 crafted ammy (or cheaper/worse, sub coven + maras)
Ars Baalos (protector's stone)
Magefist
2x SoJ
Arachs
Crafted caster boots (or just rare resist boots)
CTA/spirit swap
Renewed bone break, torch, anni, skillers, mana or mf scs (needed to hit some extra +mana)
Might or prayer merc with infinity + cure, either CoH or eth upped skin of the flayed one + protector's stone

Prebuff (join game) gear swaps:
Mang songs
+3 demon circlet
+3 demon ammy
+4-6 bind demon tome
8x demon skillers (keep bone break on)
Rest same as runtime gear

Prebuff (summon tainted) gear swaps:
+4-6 summon tainted tome (measured wrath is +4)
Latent flame rift
Rest same as prebuff join game gear

Skills:
20 Summon Tainted
20 Demonic Mastery
20 Blood Boil
20 Engorge
20 Bind Demon
1 Hex Siphon
1 Sigil Lethargy
(remaining points at level 98/99 can be put into blood oath)

This post was edited by Goomshill on Jun 12 2026 06:40am

How necessary is all the prebuff swapping? Is there a minimal prebuff version for a lazy person

Yes, its called Play Fire Lock
Tainted are OP right now, doing insane damage, weakness is immunes. You gotta min/max the tainted damage and then swap into a min max blood boil gear set.

You can enter game, clear everything just slightly slower swapping no gear as a fire lock with a 20 soft point bind demon and 1x tainted or defiler + merc and youre clearing screens too

If you are TZing an entire game and are cool with spending the small amount of time to prebuff your tainteds at the start, play taintlock
If you are trying to slam keys or bosses or tz or are lazy, play fire lock, it also clears screens

This post was edited by ahyp on Jun 12 2026 08:45am

If you spend 30+ minutes in a TZ game, taking 10 seconds to swap in stash isn't much of a hurdle.
Using 4 skillers / sunder / cube / 2 tomes / 2x4 inventory open gives (assuming just +5 tome)

Prebuff: ~34k tainted, ~48.8k jab lancer
No prebuff: ~21k tainted, ~35.4k jab lancer

That's for the max bind build. The 1 point bind build REALLY suffers with no prebuff to lancer and probably goes down to ~15-20k damage or whatever
And if you're using renewed bone break setup, you'd need to either keep a latent sunder locked in inventory for -1 skills -70% fire resist -45 life compared to a demon skiller. And if you use the renewed flame rift max blood oath setup, you lose the huge bone break advantage to your lancer and blood boil vs physical immunes, besides being much lower lancer dps. But at least you would have less prebuffing I guess.

You could recoup +3 skills if you decided to skip town portal tome and open inventory slots and just use scrolls of tp in your belt and completely full inventory with cube as only room to pick up items and tome of ID next to torch under it
That should get around ~26k tainted

Where would the mana sustain be?
How does it do vs baal? how long it take to down baal?

Do you mind showing how the prebuff works? Like what does Prebuff join game vs summon tainted mean? Haven't played lock yet and want to try this build so it's going over my head

This is what it looks like when I do it, going for absolute max possible
Obviously you can shave off half the time by just summoning at your stash with -1 skills, or cut down your charms, etc. I suppose if you were really nuts you could run a 2x sunder setup all the time, which might work with a max oath build