Among maps with huge armies, perhaps this one is unbeatable, at least among maps created by Sadow: vk.com/topic-121323606_33652172
As far as I know, the author hasn't uploaded their creations to other sites, only to VK. The map isn't difficult, but it's perfect for those who want to destroy hundreds of thousands of Azure Dragons with their several million Liches + leveling up to the maximum level and so on.
I'll also mention the remake of Armageddon's Blade by the same author: vk.com/topic-121323606_35108647