Reserves of Strength( Dragonlance Campaign Setting, p. 86)
When you cast a spell, you can choose to increase its effective caster level at the cost of exausting yourself.
Iron Will (PH) , Spellcaster Level 1,
When you cast a spell, you can decide to increase your caster level with that spell by 1, 2, or 3, but you are stunned for an equal number of rounds immediately after doing so. Your increased caster level affects all level-based variables of the spell, including range, area of effect, spell penetration, and the difficulty of dispelling the spell. You can exceed the normal level-fixed limits of a spell withthis feat, so a 9th-level wizard could use Reserves of Strength to cast a Fireball as a 12th-level wizard and deal 12d6 fire damage.
If you are not subject to stunning effects, you instead suffer 1d6, 3d6, or 5d6 points of damage when you call upon your Reserves of Strength feat.