Anyways, my idea is a bit different, anyways(Although I'd love to get permission to use that locked grappling tree he made, I have no idea if I can. I THINK I found his twitter, so I've asked.)
Current trees
Cursed/Rampage
Cursed/Gloom
Cursed/Hunter(NEW!)
Cursed/(Currently unnamed) New!
Technique/Throws(If given permission)
Technique/Grappling
Cursed/Predator(Locked)
Cursed/Cursed Form
Technique/Combat Training
Technique/Unarmed Mastery
Technique/Conditioning
Cunning/Scoundrel(to simulate claws.

New trees:
Cursed/????
Brutal Blow
Lowish cooldown.
Strike at a grappled foe, doing X% weapon damage and stunning them for X turns. This does not break grapples. At talent level 5, using this boost the damage of your grappling finisher, should you use it the turn after(Not sure how to code this)
Rising Madness
Each successive blow against a grappled foe fuels your madness, giving you +X Armor Penetration for X turns, stacking up to X times. In addition, each stack increases Hate you get from that foe by X%(So like Bleak Outcome)
Feast
Bite at your foe, doing X% weapon damage. This consumes all your hate, and does up to X%(currently X%) damage depending on your current hate. If this attack hits, it restores X Health.
?????(Currently unnamed)
Sustain
Every time you strike a Grappled foe, your hate violently explodes from them, doing X (some type.) of damage in a radius around the grappled target. Each activation costs X Hate.
Cursed/Hunter
Crazed Howl
Howl in a radius of X, sending foes fleeing with terror. If the affected can't move(such as by being grappled), they get a loss to saves and accuracy, instead.
Abduct
Sustain
You gain the ability to drag your grappled foes with you! Talent points increase your movement speed while dragging foes.
Hellish Vigor
Passive
Gain +X Life, lowers Fatigue by X%, and gives the ability to use grappling abilities in Massive Armor.
At Talent level 5, it also gives +5% Resist All.
Pounce(Could also work as the final skill of the other tree)
Rush at a foe, slashing at them wildly as you slam them to the ground. This does X physical damage, and causes them to bleed for X% damage for X turns. This initiates a grapple.
I have plans to give this a shot myself, now that my schedule is a bit freer! Outside of Abduct, none of it seems TOO hard to code, since there's other skills I can pull from generally. Idea of the class is to grab the biggest target into a room, go into a Rampage, drag the target into the center of the enemy group, then release novas of death as you wail on the dude at roughly mach 3 before finishing off the main target in a fittingly brutal manner.
Initial thought: They need a way to grapple bigger stuff. Gotta think on where to fit that.