So the kids and I were playing 40k today, and we wanted to have a big 4-way battle! However, we wanted an interesting and flavorful mission to play a little bit more dynamic than your typical "King of the Hill" game that most multiplayer 40k games seem to devolve into.
So we created "The Hidden Relic." This is a fan-created mission, and borrows heavily from Games Workshop's own missions in their Warhammer 40k Rulebook, so take with a grain of salt!
Each player selects a Battle-forged army to an agreed points (or PL if playing a narrative game) limit.
Create the battlefield and set up terrain. After placing terrain, Players then take turns placing Crates. 2 Crates must be placed within each table quarter, and the remainder within 6" of the center of the table, for a total of 12 Crates placed on the table. Crates may not be placed within 6" of a table edge.
The players roll off - whoever rolls highest determines which of the standard deployment maps is used in the battle and picks one of the deployment zones on the map for their army. Their opponent(s) then use the other deployment zone(s).
The players then alternate deploying their units, one at a time, starting with the player who rolled lowest during the deployment roll-off. A player's models must be set up within their deployment zone. Continue setting up units until both sides have set up their army.
The players roll off- whoever rolls the highest determines which player will take the first turn. The player who finished setting up their army first gains a +1 modifier to this roll.
At the end of the battle, if a model from a player's army is carrying the Relic (see below), then that player wins a major victory. If the Relic is not being carried, then the player with the model closest to the Relic wins a minor victory. If both player have models equally close to the Relic, then the battle ends in a draw. If the Relic has not yet been revealed, the game ends in a draw.
Players are attempting to find the Relic. After the Morale phase, at the end of a Player's turn, the player whose turn it is may attempt to search a crate to find the Relic. To search a crate, the player must have more models within 3" of the center of a Crate than any opponents. Models that cannot control objectives normally cannot attempt to search a Crate. One unit can only search one Crate per turn in this way.
To search the Crate, the unit rolls a D6. This roll cannot be re-rolled. On a natural roll of a 6, the Crate yields the Relic.
At that point, all other Crates are then removed from the table, and the Crate that yielded the Relic now becomes the sole Relic objective on the table. The Crate now operates identically to the Relic, as outlined in the BRB mission "The Relic" (pg 223). If 11 Crates have been searched, and yield no Relic, then the 12th Crate automatically becomes the Relic.
An Infantry model can carry the Relic by moving into contact with it - that model then automatically picks it up. From that point the Relic remains with the model (move the Relic to show this) until it is dropped, which only happens with the model is slain or flees. A model with the Relic cannot embark in a Transport, leave the battlefield, or move further than 9" in any single phase for any reason.