Psychic Miasma

Discard spells almost always sell variance as the price of efficiency, but this one sands the variance off and replaces it with patience. Because the target player picks what to discard, the opponent will always pitch their least useful card, and against a healthy hand that means a land goes to the graveyard, which hands the spell straight back. The buyback condition is therefore not a bonus you stumble into: it is the opponent's optimal play turning into your engine. A controller who is content to keep replaying a two-mana sorcery can tax the same player turn after turn, and the spell only stops returning once the opponent chooses to discard something that is not a land, which is to say once they have run low enough on mana that keeping their threats means watching their development stall. That is the grinding axis the card is built for: each cast is still only one card and the recast costs a turn plus the mana again, so it never disrupts a tempo plan, only an attrition one. The trick is that the opponent's choice is what drives the loop. As long as they would rather shed lands than spells, the spell keeps coming home; the moment they would rather keep the land, you have finally pried loose something that matters. Structurally it sits with the buyback discard effects of older eras, but the self-returning condition is the wrinkle that makes it tick.