Justice is a fan-made global mod.

You could try justifying the unicorn as an elemental (it is a creature of light, after all).

Not all unicorns are light-aligned – only one grade is.
"Light" does not equal "made of light."
This breaks the synergy with some important light magic spells (resurrection will not automatically be applied to light-aligned unicorns).

Ents

What is the basis for this conclusion? If it's a living tree, it shouldn't consist of just one element (earth)...