What is the "CrownFall" mode in Dota 2?

This is a large in-game event that lasts several months. It consists of four acts and tells the story of Shendelzare (Vengeful Spirit) and Dragonus (Skywrath Mage). The main method of progressing through the event is by playing matchmaking games, but the developers have also delighted us with mini-games. One of them is the fighting game Sleet Fighter, the gameplay of which can be seen in this video: https://www.youtube.com/watch?v=r0ppdQG3Zgs