Werewhat has finally given me the rules language I need to complete my Transmogrify novelty cube.
(It's a cube where all the creatures are Humans, but they all have werewolf rules that transform them into random creatures from a separate, shared deck, which makes them behave like double-faced cards. It's sort of like Momir Basic but with a curated collection of Monsters for your guys to transform into, only I have been pulling my hair out trying to write an emblem that adequately explains all this... etc.)
Still working on it
Anyway, I can't seem to save the image off Reddit, so here's the text:
Werewhat
3G Creature - Werewolf
Daybound
As Werewhat enters the battlefield, you may exile a creature card from your graveyard or hand. If you do, that card becomes this creature's back face and that back face has nightbound. If you exiled a card from your hand this way, draw a card.
The essential piece of technology is the phrase "becomes this creature's back face." A delightful solution.