Endurant Faith is a Unique Gloves in Diablo IV Season 15 for All classes. It comes from General Unique Pool; 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
When you would be damaged for at least 30% of your Maximum Life at once, it is instead distributed over the next 4 seconds and reduced by [15 - 20]%.
Affixes
Primary Core Stat
Maximum Life
Where it drops
General Unique Pool
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)