The mobile spawn beacon is a new piece of equipment available in the Apex Legends Lost Treasure Collection Event. You can earn points for the Lost Treasure event by competing in the Armed and Dangerous Evolved game mode, which features only snipers, shotguns, and Evo armor. If you want to bring back a teammate who has died, you will need to use the mobile spawn beacon because all respawn beacons are no longer available on the map.
When you need to revive your teammate, go into your inventory to equip the mobile respawn beacon. It will go into your hand, and you will have to find a suitable location to place it on the ground. It will become a white highlight when you can set it down and freely use it. Once it goes down, it will function similarly to a traditional respawn beacon.
Using this item does give away your position on the map. It lets everyone know where you are, and it can make summoning a teammate back into the game a little tricky. When you use it, make sure to hole up in a defendable location, and you can have your ally return without too much combat happening around them. It doesn’t hurt to have a weapon or two waiting for them, either.