Descripción
A highly obnoxious spell, counterspell interrupts the casting of another spell altogether (although Elminster has pointed out that a good arrowshot also does this at considerably greater range). When the counterspell is actually cast it does nothing but stay on hold -- further the caster cannot use another spell until he triggers the counterspell on someone. The spell only stays on hold for 5 rounds, +1 round / level of the caster. If it is not used the spell is wasted to no effect. Once triggered the target is allowed a saving throw only if his level exceeds that of the caster, even then the save is at a -4 penalty. Targets inferior to the caster in level are not allowed a saving throw.
The caster must be able to clearly see the target, and further he must decide whether or not to trigger the counterspell the moment spellcasting commences (he cannot wait as see what's being cast as is the case with the Magic the Gathering card of the same name ;) )