Mother's Embrace is a Unique Ring 1 in Diablo IV Season 15 for All classes. It comes from General Unique Pool - every Lair Boss (Initiate, Greater, Exalted, Belial) can drop it in addition to their dedicated table (one guide's Boss Loot Table Cheat Sheet).
Unique power
If a Core Skill hits 4 or more enemies, [50 - 60]% of the Resource cost is refunded.
Affixes
Primary Core Stat
Critical Strike Chance
Where it drops
General Unique Pool - every Lair Boss (Initiate, Greater, Exalted, Belial) can drop it in addition to their dedicated table (one guide's Boss Loot Table Cheat Sheet)