You can go in hide really fast if not dotted, you mez the tank and deal with the weaker opponent. It's imba in pvp. There's no chance you can apply dot with it so it don't break by himself.
It's a powerful tool that can save the ass of lots of people and reverse a situation which wasn't on your side.
The best use you can do with it in minis, is after you die and come back to where things boil up. You go in hide at the last moment before joining teammates and mez the right enemy depending on situation.
Unusable ? Come on...I don't even think I played a mini without doing this at least 3 times.