Copsicles: Icicle can use Barrier. When three of more barrier terrain markers placed by Icicle using Barrier are adjacent to a target opposing character with zero or one action token, give the target an action token.

Not a Nice Guy: Icicle can use Mastermind.

If my character moves or is placed adjacent to Icicle's Barrier tokens, will he be given a token?
No. Only characters adjacent to the Barrier tokens at the time they are placed on the map will receive an action token.

Blocking terrain can prevent adjacency, correct? So what happens if the two of the Barrier tokens are form an interesection with a character on one side of the intersection and a third Barrier token on the other side? Would that character get a token from Copsicles? See the diagram:

BB
CB

Where C is the character and B are Barrier tokens.

Barrier can indeed prevent adjacency. When an intersection is formed by two squares of blocking terrain, that intersection will block adjacency, movement and line of fire. In this specific case, C would not be adjacent to three different Bs, only two of them, so Copsicles would not cause an action token to be placed on C.