Discussion about Dungeon (Dark Elves).

And where can I find red dragons?

Is this some kind of joke?
Which castle are we talking about in the topic title? That's right – the Dungeon castle (Dark Elves).
However, they only appear in the "Tribes of the East" expansion, along with alternative updates. If the game version is lower than 3.0, you won't be able to play as them.