NHF – new heroes for Heroes V 3.1.

But this will add extra load to the map. After all, you also need to check the heroes, although they already block the exit, whether the feature is enabled or not, except that different messages are displayed there.

Added 2 minutes ago
By the way, you can make the entrance and exit tiles different ;)
You can also avoid fighting those BEHIND the portal, but to return, you need to defeat them :)

Added 1 minute ago
In IRMG, there are unlikely to be a lot of stones around the portal, and all other maps have artificial support anyway ;)

Added 5 minutes ago
By the way, I think the portals need to be reworked anyway: because they can be easily blocked by an enemy creature that won't even fight! You can also check all the creatures BEHIND the portals. Add a function to the scouting perk to reveal the troops behind the portal ;)
When touching the portal, we will reveal the exit area behind it, but then you need to somehow determine if it is possible to find out to which groups the portals belong, and if so - solve the IRMG problems almost once and for all!

Added 5 minutes ago
And there are also one-way portals, descent portals, and exit-to-land portals!

Added 1 minute ago
And if there is AI on the map, then you should only do it as RedHeavenHero said.