I didn't even know Eidolon HAD 2nd phase until I watched on youtube.
Played as Necromancer, 3rd difficulty out of 4.
When started I used 4 summon stones, tome of power, icon of defender and shot only with raven staff which spawns ravens. 1-2 Kraters is usually enough to finish 1st phase. Then boss enters his transition
animation, and I think the summons with ravens can kill Eidolon before he finishes his transformation lol.
Anyone knowledgeable can confirm what's going on and why this isn't used in speedruns?
When replayed without summons and raven staff fight went normal.

v 1.11, I think I don't have mods nor unofficial patches.