An action with this trait requires a degree of mental concentration and discipline.
Mental
A mental effect can alter the target’s mind. It has no effect on an object or a mindless creature.
Wizard
This indicates abilities from the wizard class.
Source: Player Core pg. 205
Trigger: You cast a mental spell that targets one creature, and it critically succeeds at its Will save
When your target proves resilient to your magical deceptions, you can try them again on someone else. You can Cast the triggering Spell a second time, targeting a different creature, without expanding an additional spell slot. You can do so only until the end of your next turn, and you can’t use Second Thoughts on it after the second casting of the spell.