Over a year ago I played Heroclix Online and was able to use TTPC with a character who was in the middle of making a non-free action. But is this possible? Can Superman HSS and TTPC his attack before the whole is resolved?


Themed Team Probability Control (TTPC): When
your force is a named themed team, it can use TTPC.
TTPC allows any character on a named themed team to
use Probability Control. This use of Probability Control
does not count towards any other game effects that
reference the use of Probability Control (such as meeting
prerequisites for feats). The number of times you may
use TTPC during a game is equal to the number of
characters on your force at the beginning of the game,
up to 1 per 100 points of the game’s build total. In
addition, characters using TTPC:
• Must possess the keyword that establishes the
theme of the force.
• Must not have already been given a non-free action
this turn.
• Must not be able to use Probability Control through
another game effect.
• Must not have used Probability Control in this way
earlier in the turn.
• Must immediately be given an action token (this
does not affect your Action Total for the turn)

you can use TTPC in the middle of HSS.

But not the character using HSS.

Superman is given a Power Action to use HSS. He has now been given a non-free action this turn and is ineligible to use TTPC. The underlined action in the OP says nothing about resolution of an action so as soon as the non-free action is given that figure can't use TTPC.

This is correct.

There are corner cases where you could do this, such as if you were making the attack as a free action.