Beware the Batman is committed to bringing us unlikely villains for the Caped Crusader each week. How unlikely? Well, this week’s villain is so unlikely that most of us know him as a hero! Let’s give a warm, Beware the Batman welcome to…Rex Mason! Who’s Rex Mason? You may know him better as Metamorpho: The Element Man!Please note that Metamorpho’s origin story is dramatically different than what you might have come to expect from the comics, although, given the Gotham-centric tone of the show, it makes sense. Here, Rex Mason is a security guard who is romantically involved with industrialist bad guy Simon Stagg’s daughter. Stagg doesn’t approve and sets up an “accident” for Rex, who ends up subjected to mysterious gases that change him into, well…Metamorpho. The usual “tragic monster” hijinx ensue, while Batman tries to contain Rex so he can help him, and figure out who led him into that unfortunate lab accident in the first place.Unfortunately, the episode doesn’t work. For a character with such terrific visual potential, they kind of wasted ol’ Metamorpho. Metamorpho may as well be Clayface, or the Hulk, or any number of monstrous, tragic, non-villains. Very little is made of how his elemental abilities actually work or what they might be capable of. A b-plot (which does, at least, look like it will pay off in future episodes) with Bruce missing a date with a mysterious and attractive doctor plays like something more appropriate for Spider-Man than Batman. In fact, too much of “Toxic” feels like you could swap in other characters and it would work just as well. That’s never a good sign.“Toxic” isn’t without its high points, though. Anthony Ruvivar’s Batman continues to grow on me, and he’s given a succession of tense, veiled threats to issue to Simon Stagg that are so well-delivered and timed that they’re actually funny. These are truly badass Batman moments, and it’s great to see a new voice actor (all of whom stand in the shadow of Kevin Conroy) start to make the role his own. Overall, Beware the Batman has been a solid show, despite the occasional flat episode. Let’s hope they get back to what has made this show so unique in future episodes.