Pets who cast spells use a special AI for spell casting. If the pet you have doesn't use that particular AI type then it will not cast spells.
Ah okay, was wondering with both being custom tameables.
With the Homonculous it seems he favors lesser spells over the higher ones and casting of them just seems rare when I animal lore him after multiple mob fights and see the mana level has not gone down maybe 100 points at most, though his natural mana regen might be good.
With the Ancient Fire Steed, being a rare spawn that takes place of Fire steeds i know they only use fire breath and have no magic skill rating of their own. It's just the ancient appears with it, and was just wondering if it would have the AI. Also the MAIN reason I'm asking is I actually leveled up one and breed it, guess it mutated and I got an Ancient Fire Steed with 192 magic, so I have an Ulterior motive for it being able to cast magic.