Counterspell

You pay RP equal to half the AP spent on the triggering Spell (rounded up) or equal to the RP spent on the triggering spell and Counter it, canceling its effect without refunding the AP. If the AP cost is higher than your RP, you cannot Counterspell it. 

If used against a non-Grunt target, you must pay 1 mana for each point of Focus that the target has more than you (minimum 0). 

This Spell does not provoke attacks of opportunity, but cannot be used to Counter Spells that have an AP and RP cost of 0.