Arcane Charge

Arcane Charge funnels additional arcane energy into the spell of the caster's choice, buffing it subject to DM disgression, however the strain from the raw energy takes a toll on the mind and therefore they need to succeed a cons save or be overweilmed and skip the turn.
On success the spell gets more power into it, be it more damage, longer duration etc

There are three levels of charge, Level 1, Level 2 & Level 3, each with a more difficult save in exchange for a more powerful charge.

Cons Saves:

Level 1: 11
Level 2: 14
Level 3: 17