Toxxic

From publisher blurb:

When an all around loser is recruited to be part of a chemical heist and promised a big payday, he was sure his luck had finally changed. What he didn't know was he was only brought along to be a patsy. Betrayed and left behind, locked in a chemical storage room, his clumsy attempts to escape exposed him to a multitude of dangerous chemicals which interacted with the cocktail of narcotics already in his system. His luck did change, however, and he escaped a transformed man.

Now able to turn into a poisonous mist, TOXXIC plays the big, bad super villain to get the respect he never before had, take what he wants, or gets paid to do what he was going to, anyway.