Lightning Phaser

Harness the power of lightning and arcane electricity to stop enemies in their tracks, and then deliver power strikes to said enemies

Level 3: Thunder Torque

The lightning flowing through you can take on the properties of Mjolnir.

While you wield the light hammer and have the weapon mastery for it,
It counts as a finesse weapon for you as you spin it to build momentum

For the split of momentum
You use the thunder to create an electromagnetic field, which induces torque

So you use the speed more than the  power of hit to cause momentum

Level 3: Stagnant Storm

Additionally, you can apply the slow mastery with it once a turn as the strikes weigh down on the enemy like the unmovable Mjolnir.

Level 9: Cunning Tempest

You gain additional options to your cunning strike when you hit with your light hammer

Phasing lightning(3d6): you teleport from your position to up to 10x prof bonus away

10ft radius from your position of start creates a thundering field of chaining
Reducing the movement of all creatures in it by (prof/2) + 5ft

10 ft radius of where you land creates a thundering field of liberation
Increasing movement of all creatures in it by (prof/2) + 5ft

Reflex steal (5d6)
Your thundering attacks with your hammer render enemies' nervous systems useless and bolster yours in turn
Make a sleight-of-hand check against the enemy's acrobatics (reliable talent doesn't work here)
Steal the enemy's reactions to a success
I.e enemy can't take reactions; you can take additional reactions equal to what the enemy had

Level 13: Temporal Tempest

When you use your phasing lightning, you can make the enemy teleport away instead if it fails a perception check against your sleight of hand (reliable talent doesn't work here) 

Reversing the starting and ending zones

Level 17: All-Charging Aura

At 17th level, you gain the ability to create a tempest of electric discharge around you. As an action, you may create a 30 feet emanation around you that is filled with electric energies for one minute. Creatures of your choice who start their turn within this emanation must make a Strength saving throw against your Cunning strike DC or become Charged. While charged the creature takes 3d6 lightning damage when hit by an attack. Furthermore they lose their reaction. A creature that is Charged may reroll their save at the end of their turn, ending the effect on a success. This lasts for 1 minute.

You can use this feature once, all uses refresh on a long rest.