I searched for this and didn't find anything.
Basically, in 2.4.3 they made it so the rocketbots are no longer able to be used in arena, but theres a simple way to bypass it. If you have a pet allready out, (I used a firefly) and you spam click the Rocket bot it will start to cast and it will then be out for use in Arena. It's tested, and working etc, and I was using it in Rated Arena. (Note, for it to attack the player, the player has to attack YOU first.)
Pic of proof
Thanks for reading and shiz, and if there is something wrong with this post, if one person has pointed out the fault, it doesnt need a barrage of about 4 - 5 other forum users just mimicing