Works perfectly with:
dark / forest / ice Troll
dark / forest / ice Troll Trapper
dark / forest / ice Troll Shadowspriest
You can use it as an item to upgrade your unit, as a new unit, or to create your own custom unit (since most use the same texture as the troll berserker) it also works with units created by others, but you must ask the original owner for permission.
(text translated into english by google, anything that is not understood is their fault, um I say... ask in the comments)