At-will, std, touch, 1 mana; you attempt to dispel a magical effect by touch.

Roll spellcasting skill vs the caster;

Readied

If you ready an action to do so, you may use this spell to defend yourself against an incoming targeted spell (must still win the opposed check, etc).

Reversed

1 action, ranged, 1 mana; you force extra mana into a spell, attempting to overload it. Roll against its DC (+4 bonus per extra Mana spent beyond 1); if you win, targeted spell explodes. This ends the spell, and causes medium arcane damage in a burst 2.