Aetherflux Reservoir rewards casting several spells in the same turn. Each spell you cast triggers life gain based on how many spells you have cast that turn, so the gains grow as the sequence continues. Once your life total is high enough, its activated ability lets you pay fifty life to deal fifty damage to any target.
Cheap artifacts, cantrips, and recurring spells help build the count without spending much mana on each step. The Reservoir counts spells you cast earlier in the turn even if it was not on the battlefield yet, although it only triggers for casts made while it is in play. Its own cast therefore contributes to the count for later triggers without triggering itself.
Bolas’s Citadel and Sensei’s Divining Top offer a familiar engine. Tap Top to draw a card and put it on the library, then cast it from the top through Citadel by paying one life. Repeating the sequence increases your spell count, produces Reservoir triggers, and draws through the library. You must manage both the cards remaining and your life before each payment; the sequence is not permission to ignore either resource.
Paying fifty life is a cost, so the life leaves your total before opponents can respond to the damage ability. Under ordinary conditions, you need more than fifty life to activate it and remain alive long enough for the ability to resolve. Removing Reservoir afterward does not erase an ability already on the stack. It belongs in decks that can sustain several casts in a turn and use the life gain as both protection and a finishing resource.
