Astrolabe

A three-mana artifact that pays its own upkeep tax: you spend the mana and a card to deploy it, then refund the card on the following upkeep and convert the rock into two mana of a single color. The structure is the interesting part. Most fixing of this era was either a permanent that taps for one (Mox aside) or a one-shot sacrifice that simply ate a card. Astrolabe splits the difference by deferring the replacement: the draw does not come immediately, so the card smooths a turn without ever advancing your hand count net-positive. That delay is the discipline that prices the whole exchange. You are not getting a free cantrip and two mana in the same breath; you are converting a card into fixing now and getting the card back a beat later, which means the tempo is bought up front and paid down over two turns. It reads as a wash because it largely is one, and that is the point: clean color correction for a deck splashing off-color spells, with the cantrip stapled on so the slot never feels dead. The two-mana-of-one-color clause matters too, since it makes the artifact a ramp accelerant for a single colored payoff rather than a generic tap-for-one rock. A modest, well-built piece of fixing from a set that leaned hard on flexible mana, and one whose deferred draw is a more careful idea than the rate suggests.