Orzhov Locket

Three mana buys a rock that will eventually replace itself, and that two-stage life is the whole point. Early on it taps for white or black to smooth a manabase; later, once your lands are online and the fixing has stopped mattering, four hybrid mana plus the tap and the sacrifice cash the artifact in for two cards. The rock that draws its own replacement solves the oldest problem with color-fixing artifacts, which is that they curdle into dead draws the moment your lands catch up. Writing the draw activation in symbols is the clever wrinkle: either color pays for it, so a mono-white or mono-black deck can still crack it, flexibility a rigid cost would deny. The price is meant to sting. Four mana on top of the tap and the sacrifice buys only two cards, no selection, no discount, which keeps this a floor rather than a payoff. It is built to never be the reason you win and never the reason you flood: it fixes when you are short on colors and cashes out when you are long on mana, a controlled conversion rather than a bomb. Plenty of rocks have tried to stay relevant late by stapling on an ability; few resolve the tension this cleanly, because the fixing job matters early and the draw job matters late, so the card is never asked to do both at once.