Soul Link

Damage is the one resource Magic almost never lets you recover, and this Aura quietly converts it into life on both directions of the exchange. The first trigger turns your enchanted attacker into a Spirit Link of its own, draining you back to par every time it connects; the second trigger is the genuinely unusual half, paying you for damage the creature receives. Put it on a blocker that survives its fights, or on a creature with high toughness that sits in the way, and every point of damage it soaks up refills your total. The Apocalypse design lineage is the Invasion-block fascination with off-axis Orzhov gain, the same impulse that produced larger lifedrain payoffs; this is the unglamorous engine piece underneath them. It does nothing to the board, generates no card advantage, and asks you to already have a creature worth protecting, which is precisely why it reads as a build-around rather than a maindeck staple: the life is incidental to a fair deck and load-bearing to a combo that needs to gain in bulk. Pair it with a creature that deals or absorbs huge symmetrical damage and the totals climb fast. On its own terms it is a study in a single principle, that damage and lifegain can be the same number counted twice, and the wider the swings on the enchanted body, the better the rate looks.