Examine an object for illusions as a bonus action and have advantage on investigation checks to detect them. Additionally, when an effect requires you to roll a Dexterity saving throw, you can roll an Intelligence saving throw instead. Once you substitute a save this way, you can't do so again until you finish a long rest.

When concentrating on a spell with a duration of at least 1 hour, you can extend it. At the end of its duration, make a DC 10 Intelligence saving throw. On a failed save, the spell ends as usual. Otherwise, the spell continues while you concentrate on it. Every 10 minutes thereafter, make another intelligence saving throw with a DC equal to 10+2 per 10 minutes the spell has been extended (12 after 10 minutes, 14 after 20, and so on). The spell continues until you choose to stop concentrating on it, or until you fail the save.

Humanoid

As an action, you can focus yourself on a closed-ended decision you face. That is, the decision must have a limited set of potential choices. Make a DC 10 Intelligence check. If you succeed, the GM tells you something about one of the possible decisions. Replenished on a long rest.