Time Lord Regeneration

The whole card is a conditional grafted onto a single creature at instant speed: until end of turn, the targeted Time Lord carries a death trigger that digs for a replacement Time Lord and drops it into play. That structure makes this a protection spell that reads backwards. Most one-mana blue instants that guard a creature bounce it, phase it, or hand it hexproof; this one invites the creature to die and converts the loss into a body swap. When the opponent points removal at your Time Lord, they are supplying the trigger that fetches your next one: their answer becomes your enabler. The catch is a real one. You need enough Time Lords in the deck for the reveal to connect, and if the library never turns one up, the death does nothing but replay the flavor. It rewards a critical mass of the tribe rather than a single splashy target, which is the deckbuilding tax that stops a one-mana instant from being freely splashable. The flavor read is unusually tight for a mechanical translation: regeneration in the source fiction is death-and-replacement rather than a wound that heals, and the card refuses the classic regeneration-shield template in favor of literally putting a new incarnation onto the battlefield when the old one falls.