Brogue Wiki
When the cork is popped or the flask is thrown, tiny spores will spill across the ground and begin to grow a deadly lichen. Anything that touches the lichen will be poisoned by its clinging tendrils, and the lichen will slowly grow to fill the area. Fire will purge the infestation.

The lichen produced by this potion cannot grow into spaces occupied by doors or water. As the description suggests, it is flammable, and can be used to create a "fuse" to allow the spread of fire. Monsters avoid entering creeping death, so it can be useful to fence down an early ogre.

If you suspect that a potion is creeping death, hide in a room with a door. Fortunately, creepng death cannot open doors. Creeping death also cannot take hold on obsidian, so key rooms where the key altar is surrounded by lava are great places to test potions to avoid overrunning a floor with creeping death since grabbing the key causes obsidian to form.

! Potions !
Goodglyph Detect magic · Goodglyph Fire immunity · Goodglyph Invisibility · Goodglyph Levitation · Goodglyph Life · Goodglyph Speed · Goodglyph Strength · Goodglyph Telepathy

Badglyph Caustic gas · Badglyph Confusion · Badglyph Creeping death · Badglyph Darkness · Badglyph Descent · Badglyph Hallucination · Badglyph Incineration · Badglyph Paralysis