Originally Posted by Kannojo

I believe its merely a 50% chance to dispell upon the shield slam landing or so I thought until I read the tooltip at wowhead a few minutes ago. It states:

"Slam the target with your shield, causing 420 to 440 damage, modified by your shield block value, and dispels 1 magic effect on the target. Also causes a high amount of threat."

I swear I thought the ingame tooltip said 50% chance to dispell one magic effect however. I'll edit this after work when I have an oppurtunity to look.