Hi Mariokiki,
Yes, That's just what I wrote it for. A user on steam wanted the same thing.
So place down your lava, fire, etc decal and then place a trigger zone under the decal and give it this script.
You can adjust the damage within the script to suit your needs.
Desktop: Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz (8 CPUs), ~3.6GHz, Windows 8.1 64-bit, 16 GB Ram, NVIDIA GeForce GTX 750 Ti, Display Memory: 4018 MB. Resolution 1360x768, Passmark 3528.
Laptop: Pavilion dv6 Notebook, Intel(R) Core(TM) i5-2410M CPU @ 2.30 GHz, Win 7 64 bit, 16 GB Ram, Radeon (TM) HD 6490M, 2336 MB Memory. Resolution 1366x768, Intel(R) HD Graphics 3000. (WEI 5.8)