Cooperative Mission

A Cooperative Mission is a party based mission in which the party members try to achieve the mission goal against computer controlled foes.

Cooperative Missions are started by visiting a mission outpost with the proper marker (in Prophecies, it's a yellow kite shield marker on the map, in Factions it's a round shield). Once there, players form a party (which may include henchmen), then pressing the Enter Mission button in the Party List. Everyone in the party will then be taken to the mission explorable area. To find out the details of the mission before going into it, speak to the NPC in the mission location (who is neither a merchant nor a Xunlai Agent) and he/she will explain what the story is. Each mission will make your character progress in the storyline.

Each Cooperative Mission has one or more goals listed in the Quest Log. Achieving these goals will end the mission. Failing any goal not marked as "BONUS" will result in the party all dying and being returned to the mission's outpost. With the exception of a few missions, completing a mission always leads to a new town. Some areas in the game can only be accessed by completing the missions that lead to them.

Note: The Ascension mission, in Prophecies, and the Tihark Orchard mission, in Nightfall are exceptions as they count as cooperative missions yet are performed by players individually.

Mission Rewards
There are rewards for completing missions. These rewards differ between Factions and Prophecies: Note, that characters from other campaigns do NOT get any rewards ( XP or skillpoints ) on Tyrian missions previous to Lion's Arch! Note, that characters from other campaigns do NOT get any rewards ( XP or skillpoints ) on Canthan missions previous to Kaineng Center!
 * In Prophecies: With few exceptions, each mission rewards 1000 XP and 1 Skill Point. However, each mission has a bonus objective that first must be unlocked and then completed. Simply entering the mission does not unlock the objective, instead, the party needs to find and trigger the bonus objective. Upon unlocking it, the party can then complete it (and get its reward) regardless of whether or not they completed the main objective. Sometimes completing the bonus objective may mandate that the primary objective be done too, at other times, the bonus may actually jeopardize the ability to complete the primary goal. Completing the Bonus objective rewards 1000 XP.
 * In Factions: Each mission can be completed on three different levels (listed below). Completing the mission at each level the first time gives the reward of that level. Completing the mission at the higher levels the first time gives the reward of the lower levels as well. The levels are a measure of how well you do the mission, most of the time it's a measure of how quickly you complete it, but sometimes it measures other things.
 * Standard: 1000 XP, 100 gold and 1 Skill Point.
 * Expert: 1500 XP, 150 gold and 1 Skill Point.
 * Master: 2000 XP, 200 gold and 1 Skill Point.
 * In Nightfall: Most Missions with bonus like in Prophecies, though that bonus is always numerical, so you can have Standard, Experts, and Masters, however a few have a time-counter like in Factions.

Since you can go back to a mission and re-enter it as many times as you wish (though you only get rewarded for completing it once), it is possible after you've completed a mission to go back and attempt to complete the bonus goal or the higher levels.

Cooperative Missions vs Quests
A Cooperative Mission is different from a quest in the following ways:
 * There is no Quest Giver per se. By simply going to the mission location and hitting Enter Mission you start the mission and load it's objective into your quest log.
 * If your entire party is wiped out in a mission, there is no resurrection shrine; the mission is failed and you are returned to the mission location. For this reason, it's generally a good idea if everyone in the party has a method of resurrecting party members (like Resurrection Signet). All henchmen are equipped with at least one resurrection skill that works at least once.
 * A mission area is usually a closed space not connected to the explorable areas in the game. This means that if there is an item or monster you need to find in a mission area, you need to enter the mission and find what you're looking for while in the mission. (In Tyria, this is always true. In Cantha and Elona, most mission areas are also explorable, but only after completion, with the exception of Sunjiang District, which must be crossed as an explorable area before it can be completed as a mission. However, a mission area's explorable counterpart is always different from the mission itself.)
 * Leaving a mission area while doing a mission is not like leaving an explorable area while doing a quest. If you travel outside of a mission area, then all you have done up to that point is undone and you have to start the mission over. In a quest, if you have fulfilled some of the tasks of a quest, they are not lost if you stop working on the quest and leave the zone, unless the quest-giver is found in the same explorable zone as the quest's tasks (this is especially true in Factions).

Mandatory Missions
There are 25 missions in Prophecies:
 * Only four missions are required to complete the storyline:
 * Thunderhead Keep is necessary to get to the Ring of Fire Islands, though each mission in the Ring of Fire must be done to gain access to the next one: Ring of Fire (Mission) -> Abaddon's Mouth -> Hell's Precipice (Mission)
 * Only 8 of them are compulsory to reach all the regions of Tyria:
 * All of the above, except Hell's Precipice (completing that mission does not unlock new areas)
 * Sanctum Cay is necessary to get to the Crystal Desert.
 * You must complete Dunes of Despair, Elona Reach and Thirsty River in order to gain access to Augury Rock (Mission) and hence the area of the Crystal Desert containing Tomb of the Primeval Kings and The Dragon's Lair.

In Factions all cooperative missions are mandatory to unlocking all regions and outposts as completing one makes the other unnecessary. In addition, many mission outposts will only open to players if they have the appropriate primary quest.

In Nightfall there are 17 missions that must be completed to complete the campaign. However, 3 of the required missions offer 2 different paths (either Pogahn Passage and Dasha Vestibule or Rilohn Refuge and Dzagonur Bastion, as well as either Jennur's Horde or Nundu Bay). As a result, there are 3 optional missions in Nightfall.