Eye of Baal is a Unique Focus in Diablo IV Season 15. It comes from Bartuc (Lair Boss loot table); Bartuc (Lair Boss loot table, boosted class-unique drop).
Unique power
Soul Shard Skills and their demons deal [60 - 80]%[x] damage. Casting a Soul Shard Skill increases all your damage by 10%[x] for 15 seconds, up to 50%[x].
Affixes
Weapon Damage
Critical Strike Chance
Where it drops
Bartuc (Lair Boss loot table)
Bartuc (Lair Boss loot table, boosted class-unique drop)