Actually the max size for a monster is 54x54, the sample pic in the previous post is to show the placement of 32x32 monster tiles within the 54x54 limit. (You must also bear in mind the 'v' shaped diamond boarder in the bottom right and left corners.) So the max size for a monster is something like this..
In this example the green area is for the monster/object. (the purple-pink represents the placement of other tiles.)
Hope this helps. Cheers!
