Blitz

Lost the match – shouldn't complain :). Necropolis is very weak with such a limit. Fighting with skeletons is still okay, but it gets worse later when you fight with vampires.

Well, I played it the old-fashioned way)) Necropolis is stronger for me than Castle. And I was surprised when the opponent chose Castle (especially on Mini-Nostalgia, where you choose the computer and it's all about skeletons).
So, with 121 and 3 extra castles and their hidden units, you can get almost 200 extra skeletons)).
But yes, it's difficult with such a limit.
And regarding vampires – I wouldn't level up another hero, but with vampires, liches, skeletons, and angels, the battles would be short.