Leyline of Transformation

Tribal decks have always paid a hidden tax: the type line has to line up before the payoffs do, and a single wrong word on a creature card breaks the chain. This solves that problem in the broadest way the design allows, retyping not just your board but your creature spells on the stack and every relevant card still in your hand or library. That last clause is the part that matters. Effects reading "creature cards you own" reach the graveyard and exile too, so the chosen type follows your creatures everywhere they can be, not just where they have landed. The free opening-hand deployment is the second lever: dropping it turn zero means the type-lock is live before a single spell resolves, so the card shapes the game from the first draw step rather than arriving as a turn-four build-around. Xenograft did the same retyping job for creatures in play, and the older leyline cycle established free-turn-zero enchantments as a template; this combines both ideas and then extends the effect off the battlefield. The choice is locked as it enters, so the card rewards committing to one type and punishes hedging, which is the correct place to put the friction on an enchantment that otherwise asks for nothing but a slot.