Quite simple to hex edit, I think I'll make a tutorial.. many people have no idea how to do it and it's sooo simple..
Here, you want to edit WaterLord's size, right?
If you still have the monster.ini you'll see the fields, one is the size (zoomexp).. now, if you open the monster.dat in a hexeditor, you'll search for the string WaterLord.. once you find it, you'll see the values inside the next bytes, are exactly the same as the ini. For example, the WaterLord.. his zoomexp is 100, it's the 4th field (always the 4th) after his name.
IE:
default is
5761 7465 724C 6F72 6401 0000 0064 0000 0060
That translates into
WaterLord....d...
the "d..." part is the space for the size variable, zoomexp
if you want to make him bigger, for example, 200 instead of 100 (default), you need to change it..
replace with
5761 7465 724C 6F72 6401 0000 00C8 0000 0060
That should make it. Of course I used a hexeditor to do this, but if you don't have much skills on it, you can just search for those strings and replace the 64 for C8..
used an unsigned short for that..
If you wanna learn some more hex, I suggest using HexWorkshop, it's the one I use and I kinda like it, very simple and the best I've ever found. Have fun~