I know Anet won't add a lot of content to GW1 anymore, which is why I'm suggesting a CM which makes user of content already existing.
As some of you may remember, Random Arena's haven't always been where they are now. There used to be a small island with a hill on one end and a boat on the other end of the island. I think it can actually still be seen in the D'Alessio arena of RA.
My suggestion is to add some NPC (captain) in some town at the sea with a boat who teleports you to this island. He and his crew want to get a treasure that's located there and the player's job is to protect the crew from enemies spawning in the sea, while the crew walks up and down between the hill and ship carrying the treasure. The mission continues as long as at least one crew member is alive.
The enemy mobs come in waves. It starts of with between 5 and 10 enemies and each wave adds one extra. Every x-th wave, a boss comes along with the spawn. Between waves there is a limited time, something like 30 seconds. This depends a little on the time it takes for the crew to walk from hill to ship and back
Points are awarded something like this:
- 25 points for each boss kill
- 10 points for each crew member delivering treasure to the ship
- 1 point for each killed foe
NPC skills:
I'd suggest the following skills for the crew:
-Sprint
-Divine Intervention (used when <10% health)
For the captain, who stays on the ships I'd let him use Orison of Healing
The mobs:
To avoid people being able to tank them using 55's or SF, let them have some skills taking care of those. Seeing as their numbers increase every wave at some point it'll be impossible to keep handling them causing deaths among players and crew. Possible have some snares in there to snare the crew and thus making interupting those mobs or keeping the crew clean an important task.
Rewards:
Make them comparible to other CM's.