How to complete mission 2: Everything is mixed up, truth and falsehood.

The problem is that I've essentially defeated all the lords... And it seems like, what's the issue then? Well... I decided to play extremely cautiously and simply accumulate enough troops to defeat the lords one by one, and this is what it led to: Month 25 - the path to the Necropolis (that "secret house") is blocked by 209k air elementals... And behind them are more cyclops (about the same amount)... How do I get out of this situation?