Prepare yer' Archers and tons of arrows.
Poor chickens :-)
Dragons would be difficult to get rid of, especially if you had a group of them at once...
So damn annoyed. Found a whole load of diamond in a cavern 52 squares below ground with a 3 minute walk to get down my tunnel, mined it all, avoiding loads of lava which poured in when I mined one, and THEN the game froze and I lost all my gold armour, gold tools and 15 diamond...typical. Oh well, got to grips with the game now...mine carts ftw...