Round table

The main advantage of Necropolis is that it's a castle with almost no weaknesses.

There are many weaknesses. Very weak troops (except for horses and maybe liches in some situations). Generally low hero speed. In general, the only chance for Necropolis is to use the advantages of certain map layouts and quickly acquire enemy troops in some way, because its own troops are useless in battle compared to the corresponding levels in other castles (with a few rare exceptions).