Generic Caster Gears
From HeRO Wiki
Below are noteworthy custom gears applicable to boosting magical damage output. Note that God Items and MVP Cards are excluded from the list.<be>
Caster Armor
Lounge Suit is an option when defense is not a concern, and you want to attack/cast faster while having a card slot, though armor with 3 dex may help most players more for cast speed.
Time Magician Robe is a solid option for any single target spellcaster, especially for Waterball Wizard. Downside is that it's from one of the hardest dungeon available in heRO so it can be hard to get and is pricy.