Marvel Future Fight Villain Siege is unlocked when the player completes Chapter 4 Stage 10. Villain Siege is the only place in the whole game where you can earn Chaos Tokens which are used to purchase Biometrics for Hulk, Venom and MockingBird along with Nord Stones for Speed and Universal.
I was able to unlock this feature with a maxed out level 26 Captain America and a slightly upgraded level 25 Iron Man and War Machine, used the Team Up on the boss on C4 S10 which might have been the difference between winning and loosing.
For tons more related info visit the MARVEL Future Fight Wiki, Guide and FAQ that will be updated regularly over the next month or so, after your done here of course.
Marvel Future Fight Villain Siege
Marvel Future Fight Villain Siege play much different than any other stage in the game. Your basically going after certain Heroes and Villain where you will select 3 characters to fight the 1 on 3. Where things get a little trick is when you have used a party member to engage a boss than can’t be used again until Villain Siege resets which is about every 24 hours, select a mission to view the countdown timer.
Because heroes can only be used once you going to need at least 28 characters to play each mission with 3. Your best bet is to use weak links to beat the early stages. Using only 1 character to face a boss can drastically improve the amount of stages you can complete depending on their strength and level.
The good news is that if you face a boss and loss they will still have the same HP from the fight before. This can be viewed before entering the mission with the % bar under their icon. This can be used to widdle away at the big guys until you take them down.
Because of how things are setup you probably wont be getting to the 9th area any time soon. You gonna need a ton of heroes all with high level and heavily upgraded gear. When you have member that aren’t gaining experience cause their maxed out you should switch to those who can level up more.
For more help on choosing the best party check out our Best Hero/Character post. We’ve got a lot of numbers there that will give you better direction when it come to investing time into building characters up. Our Walkthrough can also help shed some light on things to make it easier.