Just realized he can use Poison twice a turn. And now it's time for me to play him into the ground.

What part of the special power allows the second use of Poison in the same turn? Is it the "at no cost" Poison that differentiates it from "FREE" Poison ? And thus not using the same FREE action twice?

You are correct.

Heh, with Punisher Prime he can use pentrating poison at double tokened tragets.

Exact same stats/powers as Sandman so i imagine you use Wizard to switch out which one is going to be more useful against a particular opponent. Hydroman is the preferred choice against teams with minimal dmg reducers where smoke cloud/poison can do lots of free damage. The damage -1 trait is also a big deal since having imperv means they need a 4 dmg to hurt you.