First of all: you should rename the map to "The Devils Cave" or something, the file name may be whatever it is now, but please change the map name to something more general.
Off to the map itself:
Objects:
You should really rework the objects.
One thing you have to learn is how the damage formula works, instead of damage such as 5-5, you get 6-8 or whatever.
In maps like this, it can be quite bothersome.
And there is a huge lack in items, most of the mage-items are useless either way as my mana regenerates way too fast without the items.
The spells are all standard, run-of-the-mill spells (nothing special).
Heroes don't have experience, they just have 3 spells (the fighter 4, and you only get the second spell halfway in the game, way too late).
The no-damage-only-spells idea is good, but please: make more spells and redo the system to get spells, as nobody wants a game where they can only use 1 spell for the majority of the time.
And instead of triggered drops, everything is pre-set (it lowers the replay value a lot).
Triggers:
Another thing you might want to rework.
Your triggers contain awfully much leaks and are very inefficient.
The entire category Durchgänge can be done with a single trigger that would work better than what you've got at the moment.
Terrain:
I wouldn't have done the terrain like this myself, but I guess it passes for a standard terrain.
At the very least, I'm happy you didn't use cinematic doodads and you tried to make it more interesting with a few doodads.
Gameplay:
I already mentioned this, but you should add more spells.
And not only that, amke them customizable so the items actually do something.
I highly suggest you get a better triggerer for that, as your current triggering-level won't really do the job for customizable spells.
At first, the game is very interesting to play, but it very quickly loses interest due to repetitive creeps, repetitive spells (what a surprise, as you only have 1 spell until mid-game), the lack of items (and even less useful items), the creeps always having 2-3HP left because of their very small HP regen, the constant running between caves to find something etc.
In general: I like the idea of only being able to use spells to defeat enemies, running through caves to find points of interest, but you executed this very poorly.
The spells get too boring too fast, there are nearly no points of interest and the items don't even do anything valuable (make them increase the spell damage, or spell critical chance, or make certain items increase only a single spell's stats or whatever!).
Rating: 1/5 (getting close to 2/5, but only because of the idea).