Apparently the Halloween event will be somehow connected to what will be in the game on mobile, probably there will be the same event at the same time there too.
This is because within the game files, where there are the dates (they are placeholders dates so it is useless to place them) of the Halloween 2020 event, the dates of an event called HalloweenMobile2020 have also appeared.
Regarding the Halloween event, it will be called The Eternal Blight, while the name of Tome V will be called Unleashed.
Here you can see the icon regarding the Halloween challenges in the new Tome and also the banner of some new skins:
