Root Cage

Tying Mercenaries to the ground is a curious thing for green to want to do, until you remember the context: Prophecy built two rival creature engines, the Rebels of Mercadian Masques and the Mercenaries that followed them, and this exists to break one of them. Mercenaries chain their recruiting through tapping; lock them down at the untap step and the whole fetch engine seizes after a single activation. That makes this a piece of hate aimed at a single creature type's defining engine rather than at the creatures themselves, a narrower design hook than most enchantment-based answers carry. The interesting wrinkle is that it doesn't kill anything: the Mercenaries stay on the board, they just stop being a value engine, frozen mid-turn unless their controller finds an outside untap effect. Hate cards built around a denial like this live and die by how dominant their target is, and Mercenaries never quite became the menace that would have justified a dedicated answer. So it reads now as a fossil of a metagame that didn't fully cohere: a precisely engineered counter to a mechanic that the format mostly left alone. The design is sound; the demand for it never arrived.