There had already been substantial leaks of information on this collaboration but now the details have finally been released. It will only be up for 24 hours, for the whole day of 10/31 (Japan time). As has been mentioned elsewhere, all of the elemental lits in here will be skill ups for the corresponding color of rider. Ice cream Bastet will skill up regular Bastet as well. Looks like 3 difficulties of dungeon, see the images below.