Taskmaster

Reign-In-Blood

Its time the game added Taskmaster. His obvious ability should be mimicking the powers of the characters he's fighting. At the 1st level he could only copy one power of one character and they both would increase as his power level increases. Another interesting power would be a passive ability that mimicked whatever power was used against him. It could be attack powers at level 1 then increase to matching the other teams passive powers, or tile generation, etc. Maybe add a power that moves him to the front of the team a la colossus. You could also give him a multiple attack power to select from. Think Nick Fury's Yellow power, but you get to choose which power to fire off.

Tseb

Taskmaster, however, can only mimic skills, not actual powers.

Dormammu

Sounds like a good Rogue build.

ErikPeter

There's a lot of fun Taskmaster suggestions in this thread:
https://forums.d3go.com/discussion/comment/651948

I suggest you check it out.