Teval, Arbiter of Virtue

Delve has always been a self-contained bargain: exile your graveyard to make one specific spell cheaper, and the only cost is the cards you spend. Here the discount comes untethered from any single spell and stapled to a commander, so everything you cast reaches into the yard at once. The life clause is what pays for that generosity, and it does more balancing work than it looks. Delve reduces what you pay in mana, not the mana value the spell counts as, so a big-payoff spell still bleeds you for its full cost even after the graveyard covers most of the tab. That splits the accounting into two currencies at every cast: how much of the graveyard a spell empties, and how much life it drains regardless. Lifelink on a 6/6 flyer is the pressure valve, refunding the life you spill as long as the body is connecting, which quietly ties the whole engine to keeping a large evasive creature alive and attacking. The result is a graveyard-fueled ramp piece that rewards filling the yard fast and emptying it faster, then punishes you for casting the very expensive spells the delve was meant to enable. That tension (a fuel source that shrinks every time you tap it, against a life total that shrinks every time you cast) is the actual design, not the flying dragon on the front.