Necromancers with the Subjugation skill are a different story altogether;
This is already an extreme... I'm talking in general.
These are just examples. After all, dark magic can be found not only with Necropolis. And a strong ranged unit or a powerful attacker can be found not only in Dungeon. And these are not extremes...
No matter how many times I've played, I always find it and quite quickly.
P.S. In general, Prizrak, I'm not currently trying to prove that Argath is guaranteed to be more useful than "all sorts of Shaks and Goshaks, who nervously smoke in the corner compared to her." I'm just trying to prove that a hero's strong attachment to one specific unit can be costly in the late game.
Bow down and hear our cry,
Our earthly rulers falter,
Our people drift and die,
The walls of gold entomb us,
The swords of scorn divide,
Take not thy thunder from us,
Take away our pride.
G.K. Chesterton: English Hymnal