Full Magical Counter

Arcane (4th Level)
Reversible: No
Range: 0
Duration: Special
Area of Effect: Special
Components: V, S
Casting Time: 1
Saving Throw: None

Effect

With the swiping of a hand, the caster is able to send all damage from a single magical attack back at the attacker with twice the power. This spell can be cast at the beginning of a round and held onto until the caster is ready to use it. The spell can even be maintained for several minutes if the caster is willing to focus on it and not take any other actions during that time.
When an attack is made against the caster, they release their spell on the same initiative, swiping their hand at the incoming fireball, magic missile, etc. The caster then evades all damage and sends it back at the attacker twice as strong.