It especially shines in aggressive decks that are happiest to see it come down on turn 2, but it'll be great in any deck
If a spell is copied, choices made while casting it are copied, so the copy will have the same abilities spliced onto it as the original
Bound by Moonsilver is a modest Pacifism variant that, for a mana more, stops transformation, can move around to a better target, and gives us a sacrifice outlet that can kill a Demonic Pact whenever we need (not to mention Hangarback Walker or a random body so that Avacyn flips out)
It might not fit in the average cast-from-exile deck, but the ones that support it will go off like fireworks
Legendary Creature Tiefling Warlock Mythic Yongjae Choi 1/4 NOT LEGAL Standard NOT LEGAL Future LEGAL Historic LEGAL Timeless LEGAL Gladiator NOT LEGAL Pioneer NOT LEGAL Explorer NOT LEGAL Modern LEGAL Legacy NOT LEGAL Pauper LEGAL Vintage NOT LEGAL Penny LEGAL Commander LEGAL Oathbreaker NOT LEGAL Standardbrawl LEGAL Brawl NOT LEGAL Alchemy NOT LEGAL Pauper Commander LEGAL Duel NOT LEGAL Oldschool NOT LEGAL Premodern NOT LEGAL Predh Deathtouch Mystic Arcanum At the beginning of your end step, exile the top card of your library