Monsters and Mysteries in America (2013)

S4E4 Lava's a Many Splendored Thing

While exploring a planet, Rygel sneaks away from the group and gets trapped in an indestructible orange substance while pilfering treasures from a cave. D'Argo, Crichton, and Noranti set out to find him, but soon discover the cave entrance has sealed shut behind them. They are confronted by two enormous grunts clad in heavy armor, rendering their weapons ineffective against the formidable foes.