If your choice somehow ends up with an instant or sorcery card as the back face of Werewhat, Werewhat would be unable to transform away from its daybound side, so it would remain daybound even if it's night
If we can keep Teferi off the board, Didn't Say Please and Thought Collapse allow us to play a weird control-mill game, where we try to stick a copy or two of Drowned Secrets, always leave up a counterspell for whatever threat our opponent might have (while hopefully using the rest of our mana to cast cheap mill cards during our turn), and slowly mill away our opponent's library as we counter their threats
"Magic: the Gathering anniversary Facts & Figures"
Notably, however, the card does make an excellent pairing with High Perfect Morcant from Lorwyn Eclipsed
Notably, it won't copy effects that made the target creature become a creature if it isn't normally a creature
18 Rat King, Pale Piper You could do worse than have Rat King, Pale Piper as your rat Commander