I don't think we need to overcomplicate things here! Just use a high-level Tazar, like level 108, plus a potion of life and a red orb. No matter how many dragons there are, they won't be able to kill him. Start the autobattle and go to sleep! In the morning, click on the level-up button :D

Added 12 minutes later

Well, if only one stack of Azure Dragons remains, then besides one Berserker and impact magic, nothing else is needed :)

The question is whether there will be enough mana for this impact magic. :) You can use the Titan's Thunder spell!!!!! But then we risk getting some kind of chain reaction from the magic and other creatures. But we also have our own trump cards for that!!!! Use a high-level Torgrym and don't be afraid of magic. Power Field + Berserk will leave only one stack, and then Berserk and Titan's Thunder will do the rest!!! In short, there are a million options :)