Inner Strength

When you cast a spell, you can increase the caster level of the spell and exhaust yourself afterwards

Prerequisite: Iron Will, must be able to cast 1st level spells.

Benefit: Whenever you cast a spell, you can choose to increase your caster level by 1. This increased caster level affects all level based effects of that spell, such as damage dice, range, area of effect, spell penetration, and the difficulty of the spell being dispelled. You cannot exceed the spell’s maximums, such as damage dice, bonus to damage, or duration. For example, a 1st level sorcerer could use this feat to increase the damage dealt from burning hands from 1d4 to 2d4, but a 5th level sorcerer could not use this feat to increase the damage to 6d4 becase the spell’s maximum is 5d4. After you use this feat, you are fatigued during the following round, even if you are otherwise immune to fatigue. You must choose to use this feat before casting your spell. You cannot use this feat more than once per round.

At 4th caster level, you increase the caster level of your spell by 2 instead of 1 when using this feat, and the duration of the fatigue is increased by one round. Every 4 caster levels thereafter, the increase in caster level increases by 1 and the duration of the fatigue increases by 1.