Halo Wars

If you want this 1 the easy way...

1st choice is that you play with a friend... be a UNSC and let him/her be arbiter. Just let them walk to your base and activate their leader power then they walk out and back in 4 more times and the achievements should pop;)

2:nd is the version where you do this on your own...

You should be captain cutter and the enemy should be Arbiter. The AI should be on normal difficulty. Just get your Warthogs and ODST researched then wait an additional 1-3 minutes (go scout his base and see what he has done). When you think you´re ready, go to his base and kill his units then if Arbiter use Rage just use disruption bomb. Then walk strait out from the disrupted area and let Arbiter (hopefully) follow you and use his power. If you didnt get your achievement this time just repeat and get as many "killjoys" as possible every time you send a bomb.

Good luck! I did this 1 with my friend but with a little more time you can EASILY earn this 1 by yourself:)

I did this achievement against the ai.
Just go on the map blood river (1v1)

Then you need to be the UNSC, the enemy should be the profhet of regret or whatever.
Be sure to have the disruption bomb ready, make some units. Then use a scout to see if the covenant have the leader unit, if so have all your units go to the covenant leader and then trick him to your base.
Then move your units away from the covenant leader and hopfully he will use his leader power on the base .Then fire the diruption bomb near the leader, and then have your units move to the leader and lure him away from the disruption bomb and back to the disruption bomb again five times. And hopfully will you get the achievement.

I got it on first try.

The other solutions didn't seem to detail accurately the steps that needed to be completed to gain this achievement, so here's a (hopefully!) more detailed one that replicates the steps I took with a friend to get it.

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From the Halo Wars main menu, choose "Multiplayer" then "Xbox Live"

Once in the game lobby, use the following settings:

• Private game
• Xbox Live - Open party
• Players: 1v1
• Map: Blood River
• Mode: Standard
• Difficulty: Easy

One player needs to choose "Arbiter" (this is the player NOT getting the achievement this time) - the other player needs to choose a "UNSC" character (it shouldn't matter too much which one).

At this point, you should be ready to start the game.

Arbiter team member:

1. Build at least a "Warehouse" and "Temple" (the temple gives you an Arbiter)
2. Head to opposite team base
3. Press Y to enter leader mode (your character will get a purple glow) - you need to use your left stick to control the Arbiter once in leader mode

UNSC team member:

1. Once arbiter is in leader mode, press ‘up’ on the D pad and select "Disruption bomb"
2. Place near the Arbiter (or get the second player to go close to it)

Once the disruption bomb is active, the Arbiter can leave the area of the disruption bomb, and then press Y again then re-enter it. Once you leave and enter the area of the disruption bomb 5 times, the achievement should unlock.

If you don't manage to do it 5 times, you'll need to wait ~5 minutes for disruption bomb to reset (disruption bomb is only active for 1 minute).