Quag Sickness 
Enchantment — Aura
Enchant creature Enchanted creature gets -1/-1 for each Swamp you control.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL
Enchantment — Aura
Enchant creature Enchanted creature gets -1/-1 for each Swamp you control.