Feat
Overcast
A Cerberus mage's spell has no limit. —Gérard Alois
When casting a damaging spell with a slot above the level of the version being used, increase its base damage by 50% for each level of difference. This increase is additive: two levels higher deal +100%, three levels higher deal +150%, and so on.
A Level 3 Fireball cast with a Level 5 slot therefore deals 4d12 damage per CL instead of 2d12. A Level 6 Harm cast with a Level 8 slot deals 20 damage per CL instead of 10.
Overcast increases damage only. It does not grant knowledge of a higher spell version or improve its targets, area, range, duration, Saves, secondary effects, or any other property. The higher-level slot replaces the spell's normal slot; it is not an additional slot.