NHF – new heroes for Heroes V 3.1.

The load isn't that high: one iteration through all the creatures, which already exists, and 25 iterations for each portal. But heroes... yes, they run around, and I need to check each one every turn, and I won't be able to solve that.
What are the different tiles?

It seems like you can't find out the portal groups during the game.

Each object has blocking tiles, active tiles, and sometimes auxiliary tiles; for a portal, the auxiliary tile is the exit.
Or maybe it can be done by name?

Added 17 minutes later
The point is that Hafaz's "Berserk" spell won't work on all the large creatures near the portals, and that would look very bad.

Added 3 minutes later
If it were possible to determine the portal group by name, or somehow else, then no one would even notice the disabling and enabling of contact with the portal.

Added 21 minutes later
It definitely can't be done by name. Maybe you could make the hero jump over the creatures. But calculating for the heroes that might be near the portal doesn't make sense – they block just as much whether the portal is disabled or enabled...