If a double-faced card is exiled face down or put onto the battlefield face down, keep its identity hidden by using the face-down substitute card or opaque card sleeves (or both)
None of them seem likely to produce some obnoxious corner case interaction that takes over Legacy, so chalk that up as back-to-back wins for the Universes Beyond team
Doran, the Siege Tower Likely the best option as a commander for Treefolk decks, Doran, the Siege Tower introduced the ability for creatures to assign combat damage equal to their toughness rather than their power in 2007s kindred extravaganza Lorwyn
Adeline, Resplendent Cathar White has a long history of being the power and toughness equal to the number of creatures you control front-runner, and Adeline, Resplendent Cathar is one of the best creatures weve seen with that text
, Discard a card: Put a +1/+1 counter on this creature