RTF is a global modification that replaces all towns in the game.

I just think it wouldn't be bad to make a gnoll caster, but people think it would be better to have a lizard or a human.

As a person from the community, I am strongly against a human caster.
The Poles made a triceratops, so let's have a gnoll. And have you tried making Snakes like in the third part (the ones that cause frenzy)? They could be frenzy casters and cast other weak spells. Or make bulls into mages.
Did anyone have the idea to remove the fairy from the circle of fairies, put it on an angel skeleton, give it upgrades, and place it on the first level of Elementals, instead of that monstrosity that's there now?