I don't mean to hijack this demo from you, but I thought it would be simpler to use buttons instead of the text box. I have in this version changed the whole thing kinda. To add new enemies you need two sprites, an alive and defeated version. The naming convention is [monstername]-1 for alive and [monstername]-0 for downed. If you want to animate the sprites sometime down the road I can make changes to accommodate that. I have made a custom block that adds a monster to the list of monsters, you just have to type in a monster's name (Exactly how you want it to display, so preferably with a capital letter. Also, the name has to be typed, spelled, and capitalized identically to the costumes) and their health and attack values. Click a monster at any time to target it with your next attack.
The buttons I spent no time on and just put something together, they are not representative of my artistic ability. Please replace them (or ask me to) with something better.