Guard Dogs

Color-based prevention with a twist that makes the design more legible than it first looks: you point at one of your own permanents, name an enemy attacker, and if the two share a color, that creature's combat damage vanishes for the turn. The clever bit is that you supply the color reference yourself, so a single white permanent (a token, the dog's own white body, anything wearing the color) lets you neutralize any white attacker, while a colorless artifact gives you nothing to match against. The same logic cuts the other way against colorless attackers: a creature with no colors shares a color with nothing you control, so the dog has no way to bite it. The recurring activation means it can blunt one attacker per turn rather than the single use a Fog-style spell offers. What undercuts that repeatability is the math: four mana on the body, then three more every turn to point it, a rate that asks far more than the defensive value it returns. This is the stretch of Magic when prevention effects were routinely keyed to color, and Guard Dogs sits in that lineage as a repeatable, narrowly aimed version of the idea: never efficient, never broken, a curiosity built around a mechanic (matching colors between your permanents and theirs) that the game largely set aside.