Tower Of Iron Will (UA)

Source: Unearthed Arcana 71 - Psionic Options Revisited

Prerequisite: Psionic Talent feature or Wild Talent feat

Your mind’s defenses are formidable. After you or another creature you can see within 30 feet of you fails a saving throw, you can use your reaction to roll your Psionic Talent die and add the number rolled to the saving throw, potentially causing it to succeed.