Emotive Block

You create an emotional block in the target’s mind, adding an emotion component to each spell or spell-like ability he uses. This is in addition to any other components the spell already requires, and doesn’t replace the somatic component. The target’s spelllike abilities require this emotion component, even though they normally don’t need spell components.

As usual with emotion components, the target can’t cast spells (or use spell-like abilities, in this case) while affected by a non-harmless emotion or fear effect.