Fortress vs. Necropolis

Thanks for the advice. But 1. regarding the "Subjugate" spell, it does drop, but it helps. 2. what's the chance that fire elementals will appear instead of earth/water elementals!? I think we should try using Phoenixes; they might distract the Banshees/Dragons. Also, I forgot to mention that the Banshees stay in place and rarely move into the crowd to collect souls; they hang out in front of the Liches (they push them back). Skeletons absorb attacks from Hydras/Lizards/Dragons, and Zombies move somewhere and just block the path; the Lich or hero heals them. The "Chaos" skill + "Empowerment" deals a lot of damage; Meteor Shower/Fireball. Can you tell me how to make Liches cast spells less often?