Ley Veins, Archmage

Magitech

A series of magitech glands installed throughout your body can flood your bloodstream with arcane enzymes in an instant, creating a network of living ley lines across your body to stabilize your magic. When you are casting a spell and you take damage or are subjected to an effect that could break your concentration and cause the spellcasting to fail, you can activate the augmentation as a reaction to attempt a special check to maintain your concentration. For the check, roll 1d20 + 1/2 your caster level + the ley veins’ item level. The check’s DC equals 15 + 3 × the level of the spell you are casting. If you succeed, you successfully cast the spell unless the damage or effect would kill you instantly.