Toxomister
From Sonic Retro
Toxomister is a badnik from Sonic & Knuckles found in Lava Reef Zone. The badnik is a mechanical tube that produces a toxic cloud that floats up (or down, depending on whether or not the badnik is on the ceiling). If Sonic or Knuckles touches the cloud, he will lose rings at the rate of one a second and his jump height will decrease. If he touches the cloud and has no rings, he instantly loses a life. You can get rid of the cloud by spindashing. To destroy the badnik (which will also destroy the cloud), simply jump on red ball atop the mechanical tube.