In Mortal Shell 2, Umbral Stones are highly useful special equipment items. The Plague Spoils is one of the more unique ones, with the effect of consuming 40 Resolve to fire a heavy projectile that explodes above the target, scattering explosive shrapnel. To obtain this Umbral Stone, you can defeat the boss, the Wandering Shepherd.
How to Get the Plague Spoils Umbral Stone in Mortal Shell 2