>>545614540
Priest Gregor has a counter to this:
His passive gives him anti-death for 1 turn
There are 2 other gifts that give anti-death for 1 turn as well:
>Unhatched Embers
>Emergency investigation Badge++

Meaning Priest can survive 3 turns
And on turn 4, you have access to his own innate healing, EGO healing from lantern, healing from EGO gifts
He easily survives
I've actually recorded floor 11 to 15 (fights alone) Priest Gregor solo run
https://www.youtube.com/watch?v=-Rn3kEjsuF4

I encountered zero hidden bosses either, so their gifts are not a necessity