Whats is the requierement for Safe ES warlock build for Colossal ancient in hardcore? Was gona start doing this part of the collection

I found them very easy. Fought them with fade prebuf of treachery just in case.

Just a normal echoing strike build? Hm fcr? and only life leech or with life tap?

I went 75 fcr, with insight eth ca, phoenix, eni, shako, mara, soj, bk, arach, trang gloves. Merc with pride, forty, andy. Hephasto cursed/fire.
No skillers, no torch.
Defeated them in... 20 seconds?

so no life tap just life leach?

Yes. I just had a bk to leech.