So, is this a combat script? I found it on the "strategic" tab.

No. It's similar to an adventure-style additional spell, like "Portal to Town," "Astral Gate," "Call Reinforcements," or "Summon Boat." But when the spell is cast, it doesn't summon a castle ID; instead, it calls a specific script (written manually), to which you can attach a function using ControlHeroCustomAbility. It's likely that transmutations are done this way in the editor. In the NHF mod, for example, the hero Valafar can place portals on the map.


Added 6 minutes later

Will anyone answer me?

You've already received an answer.
I'll repeat (something from this):
-Incorrect file path (check the path carefully);
-Incorrect file encoding (copy a .txt file from another map, rename it, and re-enter the text if you don't know how to change the encoding).