Update 1.10.3.4: Fear The Reaper!

Improvement: Mobs spawned from events wont despawn on their own, however
once a new event starts, they will be forced to despawn unless they are
given a name tag, leashed, tamed, etc.

Improvement: Geonachs now 'make an entrance' when spawned from ore...
Kappa!

Improvement: Now that armor piercing works hard mode difficulty
multiplier defaults have been lowered from 150% stats to 125%.

Bug Fix: All mobs spawned by the custom spawners were set to not despawn
naturally, this has been fixed.