I don't know where that's from, but I can tell you it's not from any of the Warmaster or Fanatic magazines.
I really question the fairness of that in Warmaster as well- 13 shots plus cannons? Can only be attacked by flyers? It may only have a 6+ save, but it has 12 hits, no wounding rules, a crazy number of stand-and-shoot shots followed by a zeppelin load of attacks.
It's pretty much an untouchable, mobile bunch of cannons able to focus fire like nothing else in the game. On top of that it's a hero (command

- though there's no explanation of the command radius or if it needs to order itself. 500pts may be enough, but if the opponent has no way at all to threaten it then it becomes a thing of frustration rather than fun.
As presented here, this is very much special-scenario only IMO.