I would like those who have completed this battle to assess the chances of winning.
https://i.ibb.co/mJM9vd9/biod.jpg
Screenshot from a sloppy attempt, where a lot of mana was wasted, but the principle of further actions is approximately as follows: two liches stand in the corner under hypnosis. Behind them is a harpy. I cast Bloodlust and Executioner on it, resurrect it to a full stack, and cast Antimagic so that it doesn't get hit by its Titan Lightning. The titans die uselessly. Then, with a Disintegration Ray, the dragons' defense is removed, and the harpy begins to tear them apart. In this scenario, it kills about 70 dragons per round (if the author wasn't so stingy and gave at least a Blessing for the final battle, it would go faster). Every 99 rounds, the liches' hypnosis and the harpies' buffs are renewed. It seems that no more mana needs to be spent. The remaining mess in the form of fish does not pose a danger. The harpy eliminates each of them in a few rounds.
The main advantage is that he cannot counter anything at all. I don't care about his dispels and Titan Lightning – I'm the only one playing from now on. The only problem is that there might simply not be enough mana.