The Master, Formed Anew

The trick is that Body Thief triggers on cast, not on entering: the moment you put this on the stack, you get to bank a creature you already control under a takeover counter in exile, and then the creature that resolves can arrive as a copy of anything you have stashed away. That two-step sequencing is what separates the design from a Clone with extra rules baggage. You are not copying a creature currently on the battlefield; you are copying a body you deliberately set aside, which turns the exile zone into a private reservoir of templates you build up over multiple casts. The 0/1 printed body is the floor, not the intent: it exists so the copy clause has a default when the reservoir is empty. Note that exiling a creature to the cast trigger is not a death, so it will not feed sacrifice payoffs or "dies" abilities. What it does bank is the leave-the-battlefield trigger on the way out, and then the enter-the-battlefield trigger again when the copy resolves as that same creature. The identity-swap flavor of a Time Lord regenerating into stolen forms maps cleanly onto a mechanic that is genuinely about wearing another creature's stats and text. It reads like a value engine, but the real axis is tempo laundering: paying a small price now to define what a future two-mana cast becomes.