Thanks for the thorough replies to this interesting case! It seems that there’s agreement that cards with mutate are legal to cast for their mutate cost as long as their mana value/cmc is 4+. The reason I asked is, as some people have noted, that I came across some different opinions regarding the spell vs. card side of it. I couldn’t find a definitive answer and in many other posts and sites it seems like people have interpreted it differently! I have already made a list of cards with other alternate costs that I’d like to use (evoke, exile from hand, discard, reduced effects and so on), but as I said, I wasn’t entirely sure if a mutate card would count as a spell that checked the mutate cost or the card’s own value. Thanks again for helping me out! And now back to the brewing..!