Fire Lord Zuko, for example, is a red-white-black creature with firebending that adds red mana whenever he attacks, and the ability to place +1/+1 counters on each creature you control when you cast a spell from exile, or whenever a permanent you control enters from exile (which is wonderfully thematic)
Maybe its Scornful Egotist, the meme-worthy morph creature that always makes you laugh
I actually really like the idea of Vines in Elves, but the problems are two-fold
Each Equipment card with Job Select adds a creature type to the equipped creatureCleric for White Mages Staff, Wizard for Black Mages Rod, etc.along with an extra buff
Fractured Sanity is another good option, even though it only mills fourteen cards since, in a pinch, it can be cycled away to draw cards
You both have five lands on the battlefield