Ancient Cornucopia

Rock mana on a green artifact is not new; the design wrinkle is what it staples underneath. The lifegain trigger keys off color count rather than spell count, so a monocolored spell nets a single life while a five-color bomb pays out five, and the once-per-turn clamp keeps it from turning a storm turn into a life-total explosion. That structure quietly rewards the exact decks a five-color mana rock already wants to be in: the more spread your spell colors, the fatter each individual trigger, which nudges the payoff toward multicolor value piles rather than the mono-green ramp shells that usually run fixing artifacts. It is a small, honest engine. The mana ability does the heavy lifting on any board; the incidental life is a gentle tax-offset for greedy manabases, the kind of steady drip that matters over a long grind and rounds to zero in a fast one. What makes the piece coherent is that both halves want the same thing: a deck fixing for many colors gets both the mana it needs to cast the spells and the life it needs to survive casting them. Nothing here is loud, but the two abilities are built to feed each other rather than sit side by side, which is more design than most fixing rocks bother with.