Eliminate

The mana-value clause carries the entire design, and it is a sharper restriction than it looks. Two-mana instant-speed removal that hits both creatures and planeswalkers would be a premium answer at any point in the game; the "3 or less" ceiling exists to keep it from cleanly killing the fatties and haymakers that a black midrange deck most wants a cheap answer for. What you get instead is a lopsided contract: scalpel-precise against the early curve (mana dorks, aggressive one- and two-drops, the small planeswalkers that flip games open) and increasingly useless as the board escalates past it. That escalation curve is the point. Doom Blade and its many descendants gate on color or creature type; this one gates on cost, which means it stays live against exactly the threats that resolve early and want to snowball, then gracefully bows out of the late-game bomb war it was never priced to win. It is clean, disciplined removal design of the kind that shows up when the goal is a reliable answer to the bottom of the curve without handing black a two-mana catch-all: broad enough to name both permanent types it can target, narrow enough on cost that the ceiling does the balancing rather than a color or tribal restriction.