It's not like that hero/wizard is going to contest it for long (even if that is possible). So unless you have the freedom to keep on shoving heroes in there to contest it continuously she's still going to be banking a decent chunk of points. Imho Morathi, like Nagash, just seems like an inherently impossible to balance model. Just like him she has a completly unique ability putting her leagues beyond everyone else. Noone else has quite as much survivability as she has. And on a battleplan like this survivability is king, especially when paired with a decent statprofile and spells like she is. To be honest it surprises me neither of them seem to be viewed as broken by the community at large given how wildly more powerfull their special abilities are than anything else in the game.