It was a very productive day today...
I've implemented ladders, and projectiles (arrows and grenades), together with destructable ground (i.e. tiles).
Started to subclass the MovieClip class for the projectiles. Should make the code much more maintainable. I'll probably port the avatar code to use the same technique rather than code placed in frames blehhhh.
Will start coding the controls for firing a grenade/arrow :D