Necropolis vs. Dungeon

Against a Necromancer, I would definitely upgrade the Warlock's summoning skill – Necromancers have a lot of units, and Chaos magic isn't as effective. Also, it's rightly pointed out that Necromancers can get Undead Protection from Magic, Reflection, and Magic Resistance (if they're lucky enough to get Luck). You could even consider taking Chaos magic – Storm Lord – to reduce magic power (e.g., -20% to Chaos magic), and this is somewhat justified since Warlocks have fewer units. Based on my latest tests, Iranna with her Furies and the ability to create a phantom on the Furies is very strong. I recommend trying it!