Circle of Protection: Green

A pay-per-use shield, and one of the five enchantments that taught the game's first players what a sideboard was for. The Circle cycle was Alpha's solution to color hosing: a permanent that asked one mana per damage event, scaled with the opponent's tempo, and turned a single white card into an ongoing tax on a whole color. The design never expires but never gets ahead of the curve either; if the opponent untaps and plays two threats, you owe two activations. That linearity caps the ceiling on purpose. The Circle cannot be a board wipe, only a brake. Against a single large green attacker it reads as a soft Pacifism on the damage step; against a wide green board it bleeds you to death on mana.

The Circles defined sideboarding for the first decade of the game and are the reason "hoser" entered the vocabulary as a card category. They are also the reason Wizards walked away from the design: an answer that whiffs entirely against four colors and locks out the fifth is bad for competitive play and worse for casual variety. Later hosers (Rest in Peace, Damping Sphere, and the split-card hate of recent sets) all target mechanics or zones rather than colors, which is a quieter and more interesting axis. The Circles are the artifact of an earlier philosophy, preserved on the page.