Player > Feats > Focused Spellcaster
You have learned to casually ignore wounds that would interfere with a lesser spellcaster's concentration.
Combat Casting, ability to cast 4th-level spells.
If your spell would fail as a result of you taking damage either from a successful attack or from an effect that you failed a saving throw against during the casting of the spell, as a reaction you can spend a Resolve Point to prevent the spell from failing. You suffer the effects of the attack as normal, but as long as you remain able to complete the spellcasting after the attack, you successfully cast the spell.