Thank you everyone that emailed me this, Wargaming is playing the tease game with their anniversary garage:
But before you start "derpdreaming", Sturmtiger WONT come to random battles.
It was modelled yes but if it comes to the game will be in the form of a special mode event (like the Karl 8-bit).
Wonder whats being melted in the bottom?
Also there is a tiny detail, see that "ball with guns"?
Wonder if its a mention to Yuri Pasholok's book.