For this, you need to deliver the artifact to the drop zone FROM WHERE IT SPAWNS.
You cannot pick it up after it's been moved, nor can you drop it on the way to the drop zone.
This is best done with few players, or when the game has been underway for a few minutes.
I got this by hanging back for a minute, then running straight through (as an Elf, due to the speed), while all the enemies were on the other side of the map preoccupied with fighting.
Note: You cannot use skills whilst carrying the artifact or it will be dropped.