The Fire Wall is also good because it has no resistances. It works great against Gnomes.
Gnomes are also not resistant to mines. But Golems seem to be resistant. So, they are probably resistant to the Fire Wall as well.
Added 2 minutes later
The Fire Wall is also good because it has no resistances. It works great against Gnomes.
It's cool to watch when, for example, three or four squads walk along three cells of fire.
By the way, when using the wall, it's often better not to use Slow. The movement range is reduced, and in one turn, the enemy squad doesn't have time to pass all three cells at once or gets stuck halfway, blocking the path for other kamikazes.
Can you show a video of them walking across 3 cells of the wall?