The big downside here is the additional casting cost of returning a card from exile to an opponents graveyard
I remember articles where I selected random tribes to build around, random cards from all of Magic, and so forth
With some minor setup, you guarantee yourself infinite turns to do whatever shenanigans you want with all your turns
This line of thinking, however, is the farthest thing from the truth
With that all being said, here are my top choices
Ursula, Deceiver of All (212/204) Enchanted Rare ($440) The card rarities in Disney Lorcana are pretty straightforward: Common, Uncommon, Rare, Super Rare, Legendary and Enchanted Rare are the rarity designations in order