I think that monsters should attack the units of Tarth, too, because it is currently too easy to collect the loot and the xp. The Master Scouts trait should only remove the movement penalty in forests, swamps and rivers.

The Tarth Bloodline trait should be improved, because with the reduced power of the Master Scouts trait the faction would be too weak:

+ 3 initiative, + 3 attack and + 1 movement in an army of 3 or smaller.

or

Every level 1 city spawns one Bear Cub every 10 turns, every level 2 city spawns one Bear every 15 turns and every level 3 city spawns one Cave Bear every 20 turns.