Magic Slam?

[phobus]

Slam checks the armor equipped in the shoulder slot to determine if an attack is magical. Bash checks the shield/secondary slot. [You must be logged in to view images. Log in or Register.]

Edit: also, as a Shaman, your slams will never do more than one point of damage. For Warriors and Shadow Knights, as you level your bash skill, it does more damage and so does slam. But your slam acts like you have zero skill in bash (which you do). So while it's very useful for attempting to interrupt spellcasters, it never adds any significant damage.