White Auracite

Oblivion Ring wearing a mana rock's clothing. The Ring lineage has always been white's answer to permanents it cannot otherwise touch: a temporary exile stapled to a bodiless permanent, undone the moment that permanent leaves the battlefield. Here the exile rides on a white artifact that also taps for white, which changes the arithmetic in both directions. On the way in, the four mana buys a removal effect plus a permanent that keeps producing mana afterward, so the tempo cost is partly refunded turn after turn. On the way out, the vulnerability is the one every O-Ring variant carries: destroy or bounce the artifact and the exiled permanent snaps back, except now it also answers to any of the artifact removal that white decks rarely respect until it matters. The tap-for-white clause is not filler either; against a board with nothing worth exiling, it still contributes to the manabase as a rock rather than sitting dead in hand. That dual identity is the point. The two effects are welded to the same object, so they live and die together: while the artifact survives, you are getting both a locked-away threat and a source of white; the instant it dies, you lose the exile and the mana in the same beat, and the opponent gets their permanent back. It is removal you can tap for value and ramp you can lose to a Disenchant.