My opinion is that Rat Ogres are utterly worthless because they can never gain XP and thus never improve. Their stats are too low when competing against high level warbands. In the table-top, this is okay because campaigns generally have a limited number of games. But in mobile where warbands play many games, the Rat Ogre becomes easily useless as your warband levels up. Perhaps adjust where Rat Ogres can get XP if a Packmaster is in the warband? Maybe may it require twice as many XP as a normal warrior to level? That will also make the Packmaster somewhat useful as well.