Kindred
Pick a creature type you like and play the cards that reward you for it.
Elves, goblins, dragons, whatever you enjoy looking at. Kindred cards check the type rather than the individual card, so every creature you add makes the ones already on the board better. Magic called this tribal until 2024 and plenty of people still do. It is the easiest theme to build against yourself, because the question never changes: is it the right type?
Not this one?
Leave empty for no limit. Cards you own do not count.
Commanders for Kindred
Ordered by how often they are played, with the ones you own first.