Upon reaching level 17, Nanfoodle will cast Wish, and beseech Mystra to turn True Strike into the following:

Nanfoodle's True Strike

Casting time: 1 bonus action (requires concentration)

Range: 30 feet

Components: S

Duration: up to 1 round

You extend your hand and point a finger at a target in range. Your magic grants you a brief insight into the target's defenses. While you are concentrating on this spell, you may use a reaction to gain advantage on one attack roll against the target. You may choose to use this reaction after rolling to attack, but only before the result is determined. After gaining advantage in this way once, the spell ends.

Most people attempt to fix true strike by turning it into a bonus action, but that takes it too far. It makes it too good. So now it also costs a reaction, which I think fixes it. Instead of being flatly better than other bonus action options, it's now competing with Uncanny Dodge and Shield and pportunity attacks and so on.