As you make your way through the dimly lit stone corridors, the air becomes heavy with a foul, garbage-like smell. The hallway ahead is filled with debris – broken furniture, old weapons, and piles of unidentified remains.

DM Information

A gelatinous cube lurks in the hallway, hidden within the garbage. It will wait motionless until prey comes within 5 ft, then engulf them. The cube takes up the entire 10 ft width of the hallway. Secret doors are hidden behind piles of debris on both sides.

DM Tips

  • Describe the debris-filled hallway in vivid detail to build suspense.
  • Have the cube attack suddenly to surprise the party.


  • The cube will remain motionless, hidden amidst the debris, waiting to ambush passing creatures. It relies on its transparent body to go undetected.
  • When it senses movement within 5 feet, the cube will lash out suddenly with its pseudopods in an attempt to surprise its prey.
  • If its initial attack hits, the cube will attempt to engulf the target, dousing them with paralyzing gel and beginning to digest them with acid.
  • Against a larger party, the cube may slam targets with pseudopods to damage multiple foes at once before focusing on engulfing its chosen victim.
  • The cube will seize any openings to engulf immobilized or paralyzed targets. It may even retreat momentarily only to return when foes let down their guard.
  • Once a target is engulfed, the cube will single-mindedly focus on digesting them with acid, trusting its resilient body to withstand attacks.
  • If reduced to half health, the cube may attempt to flee down a side passage, content to lurk and ambush again another day.

Further Ideas

  • Valuable items may be found amidst the debris, but require excavating the filth.
  • A Javelin of lightning (1d6 charges, 1d6 lightning damage per charge used) lies hidden among the garbage.
  • Gold and valuables float inside its body (100 gp worth)

XP: 500 XP

Fellow DMs

So what’s your favorite way to use oozes like the gelatinous cube to challenge players? Any tips for telegraphing the hidden threat? What other oozes make for exciting monster encounters? Hope to hear your favorite slimy stories!


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