Sphere of Purity

Fixed prevention of exactly one point per source inverts the Circle of Protection logic: where a Circle blankets all damage from a chosen color for a repeated mana payment, this caps its help at a single point no matter how big the swing, but asks nothing of you once it resolves. That math points it in one direction only. Against a lone large artifact attacker, shaving one point off a six-damage equipment swing is a rounding error. Where it actually bites is a board of small, repeated artifact damage: a row of one-power artifact creatures, a go-wide token plan, a pinger chipping in a point at a time. Reduce each of those to nothing or near nothing and the prevention compounds across the turn. The tension built into the card is that the threat profile it punishes (many tiny artifact sources) rarely overlaps with the threat profile artifact decks tend to present (a few large metal beaters and the equipment to grow them). So it answers a real-on-paper menace that is almost never the one that kills you, a permanent calibrated for a swarm that artifact strategies have historically struggled to assemble. It reads as a defensive sketch of an early-era idea about what artifact aggression would look like, drawn for an aggressor that turned out to attack in the wrong shape.