Group Boss

"Group Bosses are powerful enemies that cannot be defeated in one combat.
To defeat a Group Boss, enlist the help of your friends. You can also help your friends by visiting their map.
You'll earn silver for each combat, and Lockboxes when the Group Boss is defeated.
Lockboxes contain a random prize, including a chance at winning a unique playable hero!
Lockboxes can be opened in the Collections menu on the Flight Deck.
Be sure you and your friends defeat the Group Boss before its timer expires, or it will escape and return later at full health!"
— S.H.I.E.L.D. Intel

A Group Boss is designed to be combated by a Player and their Allies. It was introduced in Special Operations - Vision of the Future.

A Group Boss battle is similar to a Boss battle, but must be fought several times. It costs 10 Energy and 20 Unstable Isotope-8 to initiate on a Player's map, but does not require any Resources if initiated on an Ally's map.

The Team-Up! is not present in Group Boss. Supplies, Distress Calls, and Combat Store are disabled during the battle. Ending the battle will not progress the current mission and does not add to a mission score.

For Silver dropping: From Spec Ops 8 to Spec Ops 18, Group Boss drops the rate of 1 Silver per 1 damage taken, but in Spec Ops 19 Group Boss drops the rate of 0.75 Silver per 1 damage taken.

Spec Op 8

In Spec Ops Map
Group Boss Ultron is seen on Ally's map and Ally Bar
In Ally's Map
Rewarded for defeating in Ally's map
Silver dropped from Group Boss Ultron
Group Boss will return
(No description)

In Spec Op 8, the Group Boss is Ultron. the Group Boss will spawn in any Spec Op mission after Task 6 is completed, and will respawn after 72 hours (3 days). Its class randomly changes in every battle.

During the battle with Ultron's Clone, Silver will be earned as it is damaged. If it loses 10% of its health, a single Omega Lockbox will be awarded. After three rounds, Ultron will have a chance to flee. If it has not been defeated by a player or Allies before the countdown ends, it will reset to 100% health.

If a player or ally defeats Ultron, a "Redeem Group Boss Reward" icon will appear upon entering any Spec Ops Mission. Clicking on it will award 4 Omega Lockboxes. If a player waits to click and collect their 4 Omega Lockboxes, their Allies can continue to fight Ultron at 1% and collect 4 Omega Lockboxes of their own.

Spec Op 10

Red Skull
Help Request
Spawn Group Boss

As of Special Operations 10, the Group Boss is Red Skull. Changes were made to Group Bosses, such as their tooltip will now tell the number of rounds the battle has before the Group Boss will escape.

Requests for a maximum of 10 of the player's Allies can be made to fight against the player's Group Boss. Request can be sent to both playing and non-playing friends at the Facebook version of the game.

The turn order for Red Skull was player's Top character going first, Bottom character next, then Middle character, then Red Skull's two turns.

Contributing to defeat Red Skull allows collecting boss rewards through "Redeem Group Boss Reward" icon on Spec Ops map. Taking Red Skull's health by 10% in one battle is awarded 1 . For contributing to kill his own Red Skull player is awarded 10 Coiled Lockboxes. Each contribution to ally's kills awards 1 Coiled Lockbox.

Important Note: Your requested allies are able to attack your own Red Skull right after you spawn him even if you didn't attack him at all. If you wait too much and they kill him before you attack him at least once, you will not get your 10 lockboxes.

Spec Op 11

As of Special Operations 11, the Group Boss is Blackheart.

Requests for a maximum of 10 of the player's Allies can be made to fight against the player's Group Boss. Request can be sent to both playing and non-playing friends at the Facebook version of the game.

The turn order for Blackheart is different from the previous Group Bosses. For Blackheart's turn order, the player's Top character goes first. Bottom character goes next, then Blackheart goes for his two turns. The Middle character gets the last turn in the round. Blackheart summons on the second round. His Top summoned Demon gains their turn after the player's middle character, while the Bottom summoned Demon gains their turn after the player's Top character.

Contributing to defeat Black Heart allows collecting boss rewards through "Redeem Group Boss Reward" icon on Spec Ops map. Taking Blackheart's health by 5% in one battle is awarded 1 . For contributing to kill his own Blackheart, the player is awarded 10 Demonic Lockboxes. Each contribution to ally's kills awards 1 Demonic Lockbox.

Important Note: Your requested allies are able to attack your own Blackheart right after you spawn him even if you didn't attack him at all. If you wait too much and they kill him before you attack him at least once, you will not get your 10 lockboxes.

Spec Op 13

In Spec Op 13, the group boss is Thanos and killing your own Thanos will give you 10 Inhuman lockboxes. He will change his class after each battle. By giving him a damage of 5% in a battle, you will get a Guardian Shard.

Requests for a maximum of 10 of the player's allies can be made to fight the player's group boss. Requests can be sent to both playing and non-playing friends of the facebook version of the game.

In his scrapper form, he will summon the Mission 1 boss and in his tactitian form, he will summon the Mission 2 boss.

Important Note: Your requested allies are able to attack your own Thanos right after you spawn him even if you didn't attack him at all. If you wait too much and they kill him before you attack him at least once, you will not get your 10 lockboxes.

Spec Op 14

In Spec Op 14, the group boss is Kurse and killing your own Kurse will give you 10 Mischievous Lockboxes. He will change his class after each battle. By giving him a damage of 5% in a battle, you will get a Cold Iron.

Important Note: Your requested allies are able to attack your own Kurse right after you spawn him even if you didn't attack him at all. If you wait too much and they kill him before you attack him at least once, you will not get your 10 lockboxes.

Spec Op 15

In Spec Op 15, the group boss is Arcade and killing your own Arcade will give you 10 Psycho Lockboxes. He will change his class after each battle. By giving him a damage of 5% in a battle, you will get a S.H.I.E.L.D. Point.

Important Note: Your requested allies are able to attack your own Arcade right after you spawn him even if you didn't attack him at all. If you wait too much and they kill him before you attack him at least once, you will not get your 10 lockboxes.

Spec Op 18

In Spec Op 18, the group boss is Hybrid and killing your own Hybrid will give you 10 Sandbox Lockboxes. He will change his class after each battle. By giving him a damage of 5% in a battle, you will get a S.H.I.E.L.D. Point.

Important Note: Your requested allies are able to attack your own Hybrid right after you spawn him even if you didn't attack him at all. If you wait too much and they kill him before you attack him at least once, you will not get your 10 lockboxes.

Spec Op 19

In Spec Op 19, the group boss is Bastion and killing your own Bastion will give you 10 Boombox Lockboxes. He will change his class after each battle. By giving him a damage of 5% in a battle, a single Boombox will be awarded. Prime Sentinel's level is Agent level +60.

Important Note: Your requested allies are able to attack your own Bastion right after you spawn him even if you didn't attack him at all. If you wait too much and they kill him before you attack him at least once, you will not get your 10 lockboxes.

Helping Allies

Versus Ultron Mode-B Versus Red Skull Versus Blackheart Versus Thanos Versus Kurse (Blaster) Versus Arcade (Bruiser) Versus Hybrid (Blaster) Versus Bastion (Bruiser)
Images depicting an Ally in the Ally Bar with a Group Boss in their Map. Note that Tony Stark will never have a Group Boss available in his map and his Ally Bar is used here for illustration purposes.

In the ally bar, your ally's Avatar is halved by Group Boss' avatar and moved to the left before Tony Stark which means the ally player currently attacked the Group Boss. You can visit allies and help them defeat the Group Boss.

Fighting the Group Boss has no cost. You can only help each of your friend defeat their Group Boss once per spawn. So the more times you help a friend, the more Lockboxes you receive.

Rewards

Spec Ops 8 Rewards

Rewards are only available if you defeat the Group Boss in an Ally's map. The reward instead of Roulette or like Deploy Reward, you will get instantly one of the following:

1x Isotope-8 (depending on Agent's level, except any Reactive Isotope-8)
Ant Bomb
Lightning in a Bottle
Reboot
3/5 Omega Lockbox
3
5
10
20
1
10
The Bishop
The Rook
20 Unstable Isotope-8
100 Unstable Isotope-8
1,000 Unstable Isotope-8

Spec Ops 10 Rewards

Cosmic Flame
Consumables
Deploy Drop Gear
Kree Bracers
Thermite Torch
1x Isotope-8
1 S.H.I.E.L.D. Point
10 S.H.I.E.L.D. Points
3
5
10
20

Spec Ops 11 Rewards

Spec Ops 13 Rewards

Spec Ops 14 Rewards

Spec Ops 15 Rewards

Spec Ops 18 Rewards

Spec Ops 19 Rewards

Notes

Your allies display updates at arbitrary times, at least once per day. This means that if an ally fights their Group Boss, it may take a few hours before you can fight it.
As of April 17, 2013, a player's Spec Op Maps will indicate when their Group Boss will return.
No Group Boss will appear for Tony Stark's Ally Bar Map.