I have one. It says it's a Stealer but I don't know if it's any good. Does anyone use this for battle? It's a once per battle use with one mod slot. Should I ditch it or mod it?

I tested it out with my T4, and my T13, and it worked 3/5 times to steal. Given its really low price I doubt its much good. I'd say ditch it.

It depends on your pet’s tier. IIRC it has a 90% chance to steal, which is pretty good for T3 and T4. Once you get to T5, Recycle Blaster and Soma Tablets would be preferable.