Sun's Bounty
Recover was an experiment in turning your own creature deaths into card advantage, and this lifegain instant is the simplest possible test case for it. The base effect is plain: four life at instant speed, a rate that has never moved the needle on its own. The interesting part is the deferred dividend. When a creature dies, you get the option to buy the card back from the graveyard for the same you paid the first time, which means in a board where bodies are trading every turn you can chain the lifegain repeatedly, paying as you go. The catch built into the keyword is total: skip the payment a single time and the card leaves the graveyard for good, so recover punishes the deck that wants the value most but cannot spare the mana. That tension (a recurring effect gated behind a death you have to wait for and mana you have to keep open) is what the whole mechanic was probing, and it explains why recover never spread far beyond its early-era home. The trigger condition rewards exactly the attritional, creature-heavy decks that are usually too busy to leave two mana up on an opponent's turn, and the payoff here, modest life, rarely justified the friction. As design history it documents a road not taken: a graveyard-recursion mechanic that asked you to lose creatures rather than spells, and never quite found a payoff worth the wait.
