Going to lvl30 stage 15 and stop everyday, after it's a pain...
Also i don't understand why the AI can have multiples of the same tank, that's quite OP and unbalanced. I've been ripped off by 3 Katyusha at the same time yesterday when i tried lvl30 just to see if i can do it... and nope ^^
And talking about multiples, everytime it's the best arti/destro or heavy, but not a trace of light tanks here.