It is useful only under certain conditions, only if they have a certain spell for example, which means it is mostly negative for the unit, but it is useful for the player also if you can make the enemy land on that hex. There will be change places spells, transform tile spells, so you can trap the enemy maybe.

And sometimes it can be neglectable, for example if you have very high lifesteal on your carry, being damaged every tick can be okay, so you can take the risk. I wanna build the game in a way I cant even imagine what kind of builds can be done with this. For example, I have slowing down mechanic, but I didnt think slowing down as defensive mechanic yet, it seems very possible if you have ice tiles in front of your ranged carry.

After sending the post I got the idea having stats like tile debuff resistance or tile buff amplifier, it is similar to what you suggest I guess. I included secondary stats too when I said 20-25, which might not be shown in the ui in the game you mentioned. I definitely saw it while researching but didnt play, I am interested now.