Villain Siege
In Villain Siege tab, you can play against various villains in 9 stages who seeking ISO-8. It can only be accessed once Normal 4-10 is cleared. Clearing all 9 Villain Siege stages will grant you 1,500 Chaos Tokens.
World Boss
World Boss are the End Game content of MFF. You need around 1-3 6* heroes to participate in them. They are hard in the beginning, but with the right combination of heroes and team soon you'll be a pro at finishing them. It is advisable to use high level geared heroes with good ISO sets and team to have a better chance at World Boss.