Kabraxis' Will is a Unique Pants in Diablo IV Season 15. It comes from Beast in the Ice (Lair Boss loot table); Beast in Ice (Lair Boss loot table, boosted class-unique drop).
Unique power
Wall of Agony gains the Fallen Army Variant for free and deals [20 - 30]%[x] increased damage.
Affixes
Willpower ([100-121])
Skill Ranks to Wall of Agony ([2-3])
Where it drops
Beast in the Ice (Lair Boss loot table)
Beast in Ice (Lair Boss loot table, boosted class-unique drop)