Patch 8.0.1 (2018-07-17): Redesigned. Spell ID and icon changed.
Previous: Your worm spits acid at an enemy, causing the enemy target to take an increased 4% physical damage for 25 sec.
Patch 4.0.1 (2010-10-12): Redesigned. No longer causes damage over time or reducing the armor of the target. Now causes the target to take additional physical damage for 25 seconds.