Source: http://win.wizkids.com/bb/viewtopic....cf3d0aba7deca8

OUTWIT - FREE: Minimum range value 6. Choose a power (standard or special) and a target opposing character within range and line of fire. The target can’t use the chosen power until your next turn.

If a character uses Outwit on a power such as Force Blast or Hypersonic Speed, can the target still use the granted effects of those powers such as KNOCKBACK or BREAKAWAY +2?

WK: No. When a power "can't be used", you can't use any part of that power. This includes any action activated effects, any granted abilities, and any passive effects.