I'm just trying to think the tarth ability through a bit. The differences between the intention and the gameplay since they seem to differ a bit through some bugs that are being discovered.
bonus is +3 to attack and + 3 to init when in groups of three or less. So small attack bands are really good.
Monsters don't attack your units and heroes. They will attack outposts and cities.
so this means to me that I would be able to run around and pick up early gear very easily without fear that my stacks would get ambushed by the monsters in the wild. I guess the big baddies in the wildlands won't chase me down eiether so i can go there to get a few things as well.
What it implies to attacking othe factions.
I will move my armies around in big stacks to get around so it's less finicky, but i will take the time to arrange waves of 3 unit stacks to wear down my enemies using spearmen or archers or clubs early on to get the damage upgrade on my troops.
So this ability becomes much more powerful on a dense monster map with dangerous monsters.
It seems like more of a guerrilla fighting tactic with no stealth, using the monsters in the world to protect you from the other factions but what happens to tarth when the other factions can clear away that screen of monsters. There is no stealth system in the game, which tarth could use the most loving from. If the later game armours that tarth gets is indeed lighter than the other options, perhaps an encumbrance modifier to movement speed could be useful to take advantage of that.
Some tarth ability to take more advantage of their "monsters" could be useful. Perhaps an ability to breed monsters and release them into the wild to harass everyone else seems very much in character with the game.