Cosmic Cube

Attack triggers that dig your library are as old as artifact value engines get, but most hand you a fixed reward regardless of your board. This one attaches its payoff to a single number: the free spell you cast off the top six has to have mana value no greater than your biggest attacker's power. That gating clause turns a generic top-of-library dig into a scaling payoff that gets hungrier as your board grows tall. A lone 2-power creature swings for a cantrip's worth of value; a 6-power threat opens the door to genuine haymakers, and a truly oversized attacker lets the whole top six become fair game. The card rewards vertical boards over wide ones, which is a deliberately unusual axis for a value piece: where similar artifacts scale with a static reward, this one asks you to assemble a power curve and pushes you to keep raising the ceiling. Ward does not make the artifact hard to kill so much as it prices the answer: an opponent has to find two extra mana on top of their removal, which most often means the artifact survives an opening they can't fully fund rather than one they can. The friction governing it is honest: the free cast is capped by combat math you have to build yourself, the leftover cards go to the bottom in random order (no repeatable stacking), and the trigger fires only on the attack, so a defensive stance renders it inert. It is a rate that scales with ambition rather than a fixed number, which is the more interesting way to design a payoff.