From Dungeons of Dredmor Wiki

Damage: 8 5 5

"This spell causes rock to explode from beneath an enemy's feet."

This spell is invoked by the Glacial Burst and Rockburst Trap traps. It is also an on hit effect of the Axetar and Axekeytar.

It is also possible to enchant a weapon with this effect at an Anvil of Krong. It will show the text "pounds your enemies with rocks."