Spiritualize

The whole effect rides on one combat exchange, and the design leans hard on open-ended phrasing: any damage the chosen creature deals, by any route, becomes life. A blocker that trades into a gang of attackers, a trampler whose excess connects, a creature whose ability deals damage to several targets at once: each instance is its own lifegain event, so the ceiling scales with how much carnage you can funnel through one body in one turn. That makes it a defensive cantrip wearing a combat trick's clothes, since the rider replaces itself most of the time and rewards stacking on a creature that hits more than one thing. The card-draw clause is the only reason a pure lifegain instant at this cost earns a second look: buffering a life total against a fast race is marginal on its own, but doing it while drawing asks almost nothing of the deck. The catch is the target requirement. If the chosen creature is removed in response, the spell fizzles entirely and you draw nothing, so the cantrip is not free insurance; it is contingent on the body surviving long enough to resolve. It also reaches into combo space, because granting an effective lifelink that triggers on any damage dealt pairs with anything that loops or multiplies combat damage, and the gained life can feed a payoff that cares about life totals rather than the combat itself. Most of the time, though, it is a one-shot lifelink grant with a card attached.