I don't get what all of this complication is about. It's not necessary to change pve... You just need to allow Scrider to have an attack that can kill a person in 1 hit if they are on his head. Also for the people that lure Scrider (which is also considered riding), you need the Scrider to have attacks that make it much more difficult, resulting in people alternating the position of luring in one round of Scrider. If you can get through a boss with just one person luring the entire round, it doesn't take long for the other 3 teammates to finish him off.
