Handsome Jack Doppelganger Rundown for those interested:
Skill: Expendable Assets
Summons two holographic versions of himself(think Handsome Jack boss fight in BL2). If they die they respawn next to you. You can also press LB to cancel early and get a shorter cooldown. The holograms fire the shocky things from their wrists that Jack does in the beginning of the game.
Skill tree 1: Hero of this Story
Focuses mainly on upgrades for the digi-jacks. End game is the first digi-Jack is a badass and the ones after have a chance of being badasses. Also a lot of upgrades for you and your digi-jacks, including increased health, fire rate, etc. Also has one skill called "Inspire" where Jack shares his "words of wisdom" every few minutes. This is more than likely hilarious.
Skill tree 2: Greater Good
Very stack based tree. There are certain stacks for digi-Jack's dying, getting kills, etc. For those who don't know, stack abilities give bonuses that get bigger as you accumulate more stacks. The end game for this one is a digi-Jack dying grants you second wind(i.e it will be almost impossible to die when you're ability is activated).
Skill Tree 3: All about guns. Has a bunch to do with weapon swapping, like it being faster and getting increased fire rate every swap. The end game is your gun you swapped to gets a bonus based on the gun you swapped it out for:
Dahl- 50% recoil reduction
Hyperion- 30% more accuracy
Jakobs- 30% more weapon damage
Maliwan: 25% elemental damage increase
Scav- 35% bigger magazine size
Tediore- Reload Speed up 35%
Torgue- 25% more explosive damage
Vladof- 35% increase in fire rate
Miscellaneous:
Dialogue between Jack and his doppelganger is hilarious(he develops a crush on himself basically)
Actual doppelganger dialogue is pretty funny too
He is free if you bought the season pack.
Thats all I got right now, im still working on my first TVHM with Claptrap so it might be a while before I dig deep into Jack's skill trees. Right now im looking at going with the one focused on digi-jacks though, as I think summoning badasses would be tight.