Attune with Aether

Banned, and the ban is the whole shape of its history. It looks like a fixing spell that happens to leave you with two of a parallel resource, but the design problem it created was the opposite of fragility: a one-mana sorcery that smooths the manabase, replaces itself, and pays the entry toll for a second mechanic. Energy was meant to accumulate slowly across many cards, so a deck got punished only if its individual energy producers cost real tempo. This priced the door to the whole engine at a single green mana, and that turned out to be too cheap. A green one-drop that fixes mana, draws a land, and funds a second strategy is doing three jobs while asking nothing back. The thinning-and-shuffle clause is incidental; the two energy counters are the part that bent a competitive format and got the card pulled from it. As a study in how resources are paid for, it is a clean lesson: a payment stops being a payment when it costs you nothing to make.