Is the Psi Warrior Fighter's Psionic Strike compatible with the Brace Combat Maneuver?

Question

Psionic Strike. You can propel your weapons with psionic force. Once on each of your turns, immediately after you hit a target within 30 feet of you with an attack and deal damage to it with a weapon, you can expend one Psionic Energy die, rolling it and dealing force damage to the target equal to the number rolled plus your Intelligence modifier.

Brace. When a creature you can see moves into the reach you have with the melee weapon you're wielding, you can use your reaction to expend one superiority die and make one attack against the creature, using that weapon. If the attack hits, add the superiority die to the weapon's damage roll.

I would imagine not considering the "once on each of your turns wording" but I just want to make sure. It would be super cool if I could use Brace's attack, stack Psionic Strike on top it and then use Telekinetic Thrust.

Answer 1

Only in very rare circumstances

Because psionic strike must be made on the Fighter's turn and Brace uses the Fighter's reaction to another creature's movement, it is extremely unlikely, but not impossible, that the two could be used together.

If, for example, an enemy held its action (a move action) and declared the trigger for that held action to be something that happens on the Fighter's turn, it's possible that the enemy might move into the Fighter's reach, thereby allowing the Fighter to use its reaction for an opportunity attack on its own turn.

In this situation, the Fighter could add the superiority die and psionic die (plus intelligence modifier) to the attack of opportunity the Fighter was entitled to make.

So it's possible for it to happen but very, very unlikely.

Answer 2

You can't do that, for the reason you mention. The PHB wording for a reaction states that:

A reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else’s.

If you're using it during another creature's turn, you don't meet the "on your turn" requirement to using Psionic Strike.