Blazing Wheel

Blazing Wheels are part of the Dungeon rather than something you summon or trigger. They generate through normal enemy spawning, and they strongly favor stretches of the Dungeon backed by tiled wall. They can appear in front of other wall types too, just much less often, so a room with the wrong wall is not a guarantee of safety. Like any other enemy they appear and vanish just off screen, so an empty corridor can hold one by the time you walk back through.

It has defense, a hit sound, a death sound and immunity to a few debuffs, none of which you will ever observe, because nothing in the game damages it. Treat it as terrain that moves. It rides along whatever solid surface it is touching, floors, walls and ceilings without distinction, at a speed that leaves very little reaction time in an unlit corridor. Automatic weapons and sentries used to waste attention on them, which was patched out.

• It glows. Look for the light before you drop into a dark room and you will usually see it coming around the corner.
• It falls straight through platforms rather than riding along them, so a platform walkway built above the floor is safe ground.
• Hanging off a hook in midair puts you clear of every surface it can use. A multi hook holds that position while you fight whatever else is in the room.
• Wall one into a pocket only two or three tiles across and it despawns. That is as close to killing one as you can get.
• An open door is an open road for it. A closed door stops it dead.
• Actuated blocks read as solid to it, so actuating a floor out from under you does not remove its track.

Being a real enemy has consequences that catch people out. It can damage the bound NPCs you came down to rescue, so a wheel loose in the room with a captive is a rescue on a timer. Teleporters will move it like anything else. Detection accessories count it among the creatures nearby. And it is not confined to the Dungeon: give it an unbroken run of solid surface leading outside and it will eventually turn up somewhere it has no business being. If you strip away every block it was riding on, it flies off toward the nearest surface it can find rather than disappearing.

Despite being visibly on fire, it does not inflict On Fire! It just hits you.

It shares its movement code with the snail, of all things. The concept is lifted from the Hothead in the Mario games, which climbs walls and ceilings the same way.