Alchemist's Gift

The choice is the whole point. A one-mana combat trick that pumps and grants a keyword is nothing new, but folding deathtouch and lifelink into the same modal instant hands one card two entirely different combat-math problems. The deathtouch half turns any blocker or attacker into a guaranteed one-for-one trade: point it at a creature stepping into combat and the biggest thing on the board dies to a single point of damage. The lifelink half is the racing tool, swinging a damage race by the full value of a connected attack plus the bonus, and doing it at instant speed so the opponent commits blockers before they know which mode is coming. Because the mode is chosen on resolution, the trick threatens both lines at once, and the defender has to play around the worse of them. That dual threat is what separates it from a plain pump spell: the same mana is buying two answers, and neither is revealed until it is too late to adjust. Black's access to a clean pump effect has always been narrow (the color pays for its combat interaction in removal and sacrifice, not in Giant Growth effects), so a modal instant that can either assassinate a blocker or stabilize a life total covers ground black usually reaches for two separate cards to handle.