I'm probably going for a 20 BO, 20 Bind, 1 Engorge, Fire Sunder build
Probably getting TZ Lister, he is a good mix of damage and tankiness.
Might also be a Fana Lister, I dont like Cursed + HFreeze as much after the 5% AD nerf (I know it still procs, but much less consistently). And Fana IAS helps Tainteds too
Although HFeeze might help merc stay alive more, hmm...
I finally put together the obsession 125 fcr setup, albeit with coven + maras not shako + 2/20 ammy so far, and even using just 1 point blood oath AND a tz cursed spearwoman mob with 1/2 the hp, I haven't had get low on hp a single time so far, let alone come close to dying. I mean, its the difference of 1.3 million vs 2 million vs 2.6 million, its still all in the millions.
I cannot stress how critical it is to use HF+amp to proc amp consistently both for the blood boil you
should get with the max engorge build, but even just for the demon DPS. The difference any of the auras makes to your demon/merc/tainted is very small. Maybe 1.1x dps on a demon, 1.05x on tainted. The difference amp damage makes can be 2-3x. Against phys immunes with bone break it can be 40x more damage.
There are still plenty of fire immune mobs where even if your spearwoman
will kill them on her own, she does it slower than if you spam blood boil because of the massive aoe. Packs of fire immunes who are outside of the one-shot range of 22% of tainted damage. And that blood boil is reliant on amp damage, and amp damage is reliant on holy freeze. 5% proc on melee attacks might as well not exist, but against clumped enemies there's barely any difference from pre-nerf and post-nerf demon, in 4-6 seconds you could have 95%+ chance to proc amp.
Lister is generally mediocre as a choice, he's more or less the same as an urdar except with no regen/cb. Urdars can easily hit the same HP cap, maybe not quite as much %AR but probably have close to 95% CTH anyway with conviction. But urdars are worse than spearwomen because the HP really isn't a bottleneck here