Buster Sword

The interesting design choice here is that the payoff scales with the damage number, not the equip cost. A +3/+2 buff is a modest rate for a three-mana Equipment, but the second ability turns combat damage into a two-part reward: a guaranteed card off any connection, then a free cast of anything in hand whose mana value is at or below the damage dealt. On an unblocked bare creature that initial connection already reaches for cards worth five and six mana, and every point of extra power widens the ceiling on what you get to cast for free. That coupling is the whole engine: the buff exists partly to raise the base body, but its real job is to push the damage number high enough that the free-cast clause reaches the expensive spells you actually want to cheat out. It rewards stacking power (double strike, trample bleeding through blockers, other pump) because each extra point of face damage is another mana value of free spell. The friction is that it lives entirely in the combat step: no connection, no draw, no free cast, and the equipped creature has to survive to swing and land the hit before any of it happens. It reads like a fair Equipment and behaves like a repeatable spell-cheat bolted to a swing, paying out on tempo rather than on stored energy.