Hecaton Chasm is a Unique Ring in Diablo IV Season 15. It comes from Astaroth (Lair Boss loot table); Astaroth (Lair Boss loot table, boosted class-unique drop).
Unique power
Tyrant's Grasp deals [100 - 120]%[x] increased damage and summons 5 additional demonic hands in all directions.
Affixes
Willpower
Skill Ranks to Tyrant's Grasp
Where it drops
Astaroth (Lair Boss loot table)
Astaroth (Lair Boss loot table, boosted class-unique drop)