Mystic Boost is a blessing.

This singular skill synergizes so well with Fury. You can make duelists Fury users now, which makes me happy, because I want to make a Mage Duelist Kaze.

But Fury isn't the only thing is synergizes with. Here's a list of things:

Eir's Weapon (Obviously)
Alm's Falchion Refine
Atk/Spd Push
Carrot Weapons (1st Easter)
1st Summer Weapons
Tanks that don't need QR or can use QR in the seal slot
Potentially Eldigan, (Depending on if a cavalry restriction exists) Fallen Celica, and Bartre

Those are just for the Healing ability.

It also has Wrathful Staff cancel and Adaptive Damage Cancel. Julia and Deirdre are two prime candidates for that because theur weapons are dragon-effective. Otherwise, it helps with staff tanking, and ranged dueling with dragons.