This is one of the new creature cards that comes with a spell attached, and in the case of Emeritus of Ideation, it features an OG Power Nine spell in Ancestral Recall, which it can cast any time the card is prepared (read all about prepare and the other new mechanics in our Secrets of Strixhaven mechanics guide)
Keep in mind, if your opponent is playing Teferi, Hero of Dominaria, you should probably make a construct token so, if your opponent untaps and plays Teferi, Hero of Dominaria and tucks your card into your deck, you'll be able to at least kill Teferi with the Construct token
All these variables influence which method is best
That being said, here are decks that any player with a basic understanding of how to play MTG can get into without too many complications
Im also strongly considering the idea of creating an Azorius deck that contains Arcane Adaptation just to be able to get lots of miles from Preston
I know Ill be on the lookout for new ideas in the coming weeks, so if any cards that stand out for you, be sure to let me know on Twitter at @Rappaciousone