Khalni Gem

The bounce is the price, and it is steeper than the four-mana cost suggests. Most rocks that fix two colors do it cheaper with no strings; this one returns two of your lands to hand the moment it enters, setting your board back before it can move forward. The trick is in the timing of that setback. Returning two lands is pure tempo loss on a clean turn, but it stops being a tax once those lands have already done their work: a creature-land that has attacked, a land whose entry payoff you would happily collect twice, a land with a sacrifice clause you would rather replay than spend. The Gem turns a one-time tempo hit into a way to launder value out of lands that have outlived their first purpose, and it replaces them with a rock that taps for two of any single color, smoothing a greedy manabase the way two basics never could. That conditional flips the whole evaluation: among vanilla lands it is a clumsy fixer, but among lands that want to leave play, the downside is the engine. It rewards a deckbuilder who reads the board before casting rather than after, where the cost line lies and the surrounding cards tell the truth.