Crown of the Guardian

(3) Set: Initial hits from Flamestrike, Cone of Cold, Frost Nova, Blast Wave, and Arcane Explosion have a chance to trigger a rewind effect. On rewind, Arcane spells deal 10% additional damage, and Frost and Fire spells deal 20% additional damage.

(5) Set: Your spell critical strikes conjure a magical barrier that absorbs 350 damage. While the barrier holds, the damage you deal with magical spells and effects is increased by up to 42 and the threat you generate is reduced by 15%.