MTGNexus

need to be refreshed on this, gonna start playing my dino deck again.

for example, have Ranging Raptors in play. Pay Illuna, Apex of Wishes mutate cost, then put Illuna card on top of the raptor. The mutated creature will be a 6/6 with all of Illuna ability + all raptor ability?

but if I put Illuna on the bottom. The mutated creature will be a 2/3 with all of Illuna and raptor ability?

Yes. What the mutate reminder text means by "They mutate into the creature on top" essentially means that the resulting permanent has all characteristics of the top card - name, mana cost, typeline, abilities, and power and toughness - but with all of the abilities of cards below it added. In this way you can have a Ranging Raptors that has all of Illuna's abilities or an Illuna, Apex of Wishes that has the Raptors' ability.

I see. Thanks for the info.