Player > Feats > Spell Focus
Through careful study, you have developed methods to make your spells harder to resist.
Ability to cast spells, character level 3rd.
The DC of spells you cast increases by 1. At 11th level, the DC of your spells instead increases by 2, and at 17th level, the DC of spells you cast instead increases by 3. This bonus does not apply to spell-like abilities.