The Rules of Invasion is a three phased objective game type with two teams, Spartans and Elites. A phase ends when the objective is complete or when the phase timer runs out. The attacking team wins once they successfully complete all three objectives. The defenders win if they can run the phase timer out on any phase.

Important InfoFirst things first! There are a multitude of things that you need to know about how the internal structure of an Invasion gametype.


There are 3 different objective types available for each phase (27 different permutations)
Each objective type has different requirements that the forged map must support.
Invasion supports fire team player spawning and spawn locations.
Forge objects can be setup to appear or disappear in a specified phase.

Invasion Game Variant SetupCustom games should only use the "Invasion" variant and never Invasion: Boneyard or Invasion: Spire. The invasion options can be configured to change who is attacking, Spartans or Elites, and what the objective is for each phase.

Invasion ChecklistThis is a list of everything your Invasion map should have:


3 total objectives, 1 for each phase
Initial, phased and backfield spawn locations
A Safe Zone to define the boundaries of the map

Important Forge Object Properties for InvasionGame Type Specific:

An object set as game type specific will only show up in game types that include the Forge object label in its list of predefined labels. Any invasion specific objects that do not already have an invasion specific label should be labeled "Invasion.

Labels:

Labels are a name that can be given to any object and can define game behavior. Each object can have a single label selected from a list of labels supported by the game type being Forged. Note: You must be Forging in Invasion to see the Invasion labels.

Boundary Volumes:

Boundary volumes must be given to all hill locations and flag capture locations, otherwise it will never detect a collision, and the objective will not function.

Teams:

The two team colors in invasion are assigned to the species as opposed to attackers and defenders. Spartans are assigned to red and Elites are assigned to Blue. This makes it important to correctly set the game option, Invasion Options Attacking Team, to the correct race before starting a game of forged invasion.

Getting StartedTo begin creating an invasion map, select the Forge lobby.
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1. Select Invasion from the Game Type field
2. Select the Map you wish to modify
3. Start the Game
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Once you are in Forge, Enter Edit mode by press up on the D-pad or select it from the Start Menu. For the most reliable results, it is recommended that you delete all objects from the map so you only have objects that you have placed.
Creating ObjectivesThere are 3 types of invasion objective and they function much like their stand alone equivalent.


Territories
Assault
Capture the Flag (Capture the Core in the case of Invasion)
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While an Invasion map only needs to support one objective in each phase, it can be setup to handle all cases. There needs to be at least one objective for each phase to complete a round of invasion.
Setting up a Territories ObjectiveThe Territories objective type requires a single object to function. There can be any number of territories per phase.

To setup a territory we need to place an object on the map and give it the INV_OBJECTIVE Label:
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1. Enter the place object menu
2. Select an Object (Objectives\Hill Marker is a good choice)
3. Press X to edit the objects properties
4. Select the Advanced option and the Game Type Label property
5.Change the value to INV_OBJECTIVE
Now that you have a territory object, it is time to define the boundary volume:
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1. Press X to edit the objects properties
2. Set the shape property to anything but none
3. Increase the size of the width, top, bottom and length to the desired size
Lastly assign a phase for this territory objective to be active.
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1. Grab the territory object
2. Enter the Object Options
3. Enter the advanced sub-menu
4. Set the Spawn Sequence field to the phase in which this objective will be used (1,2,3)
Setting up an Assault or CTF ObjectiveAn assault or CTF objective requires taking an object (bomb or core) from one location to one or more destinations. An assault objective requires the carrier to plant the bomb, a countdown within the zone, while a CTF objective only requires the carrier to enter the objective zone.

First off we need to create the location where our Bomb/Core object will be spawned.

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1. Enter the Place Object menu
2. Select an object to spawn the Bomb\Core on(Objective\Capture Plate is a good option)
3. Press X to edit the objects properties
4. Select the Advanced option and the Label property
5. Change the value to INV_OBJ_FLAG
Next we need to place the object which will be used for the Bomb\Core Destination. [ Register or Signin to view external links. ]
1. Enter the Place Object menu
2. Select an object to spawn the Bomb\Core on (Objective\Capture Plate is a good option)
3. Press X to edit the objects properties
4. Select the Advanced option and the Game Type Label property
5. Change the value to INV_OBJECTIVE

The destination location needs a boundary volume.


1. Press X to edit the objects properties
2. Set the shape property to anything but none
3. Increase the size of the width, top, bottom and length to the desired size

Lastly assign a phase to assign a phase number to each location.


1. Grab the territory object
2. Enter the Object Options
3. Enter the advanced sub-menu
4. Set the Spawn Sequence field to the phase in which this objective will be used (1,2,3)
Setting up Multiple Objectives per PhaseThere are some considerations when overlapping objectives per phase. Any object labeled as INV_OBJECTIVE will count as an objective. So the objective for Assault Phase will also count as a territory objective which means only one object labeled with INV_OBJECTIVE needs to be present to support all objectives.

Setting up Spawn LocationsThere are three types of spawn locations that can be setup for Invasion:


Initial Spawn - The players will spawn at the start of the game at these locations.
Backfield Spawn - These spawns can be used during any phase by anyone on the associated team.
Phase Spawn - These spawns are only active in one phase and are associated to a fire team.

While the attacking team can be changed from the Invasion game options, this will not switch the team positions around. When a player dies they can choose to respawn on a member of their fire team, at a backfield spawn or any phased spawn available to their fire team.
Setting up an Initial Spawn Location
Initial spawn locations need to be set for each player on each team. Initial spawns are not affected by fire team.
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1. Enter the place object menu
2. Select a Spawning\Initial Spawn object
3. Press X to edit the objects properties
4. Set the team property to either red or blue
Source: Bungie.net
PART 2 Coming Soon