Walkthroughs for custom maps.

Thank you, very interesting!
I didn't know about this trick. But it can be used not only for the Fire Wall, but also for Mines and Sands. And, of course, not only for Cyclops, but for anyone.

It allows you to move archers through all three cells.
Impressive!
There are more screenshots in the comments above.
It turns out that the Fire Wall can also be used as a makeshift force field.

Position your troops using tactics in a corner of the map or in some other convenient terrain.
The main point here is to have weak, single units standing behind the wall.
The AI won't enter the fire because it doesn't want to take a lot of damage from the wall and exchange it for a small amount of damage to a single unit.

Also, two hexagonal units won't stand head-on in the fire.
That is, on the edge of the map, your single-hex fairy will be "invisible" to griffins, for example, if it stands behind the Fire Wall, but not directly on the edge of the field, but one cell forward.