Books tend to offer card advantage, so card draw, discard, and hand size will be recurring themes, but we could see lots of others
Being an enchantment would normally be a downside on a creature this expensive since it dies to enchantment removal as well, but it has hexproof anyways so that matters a lot less
I am a big fan of lifelink in Commander these days, and Metamorphosis Fanatic is my kind of card
Forest of Giant Plants The Stadium card that got banned for being too good, Forest of Giant Plants, is a legendary piece of tech in pretty much every meta Grass-type deck during the time, and was a key player in allowing the player who goes first to put their opponent in an item lock before they even get the chance to play
Imprisoned in the Moon is not a card that you build an entire deck around, but it is a flexible role player that gives blue the ability to nullify cards that it normally doesn't interact well withlands and planeswalkers