In preparation for newer versions of Minecraft, all Entity classes should be unique, i.e. no 'sub-types' within an Entity class.

This means each variant must have its own class and be registered separately, negating the need for my CustomEntityList and related classes.

See 1.12.2 Skeleton and Wither Skeleton in comparison to their earlier versions.

It is already possible to specifically summon subtyped mobs, e.g. /summon zeldaswordskills.wizzrobe ~ ~ ~ {WizzrobeType:1} will summon an Ice Wizzrobe.

Obviously /summon zeldaswordskills.wizzrobe_ice will be easier, but I did not know they could be summoned with the vanilla command as they are, a fact which makes this issue unimportant for current versions of the mod.