Halo Wars

The "Debuff Skulls" are:

Fog
Sickness
Rebel Sympathizer
Rebel Supporter
Rebel Leader

To gain this achievement, begin the first mission on Easy difficulty and press start as soon as you take control of Forge. Navigate down to the the Skulls menu and enable all of the above Skulls (anything that says your score will increase is a "Debuff Skull").

Then just play the mission as normal. None of these Skulls make it that difficult, since you're on Easy mode and since it's a fairly straightforward mission to begin with, and they shouldn't pose too much of a problem. Try your best to blaze through the mission so you can come in under par time and maximize your points.

The achievement unlocks as soon as you beat the mission and are taken to the mission stats screen.

EDIT: As Wazup970 mentioned in the comments, a link to where all the Skulls are found would be helpful. So here it is!

http://www.gamesradar.com/f/halo-wars-guide-to-skulls-and-bl...

Another way is turn on the skulls (Fog, Sickness, Rebel Sympathizer, Supporter, and Leader) then play easy on the 12th mission, which you use the cyclops to repair the generator.

Note: If you repair it quick enough, you will also get the Handy with tools achievement. (use heal and repair on the generator to help repair it quicker)

very easy. play the first mission on easy. as soon as you have control, switch on fog, sickness, rebel sympathizer, rebel supporter, and rebel leader. just complete as many objectives as possible and youll have easily 35,000 points, where 29,999 is enough to get gold.

This is a super easy achievement if u know what to do. First pick Mission 1 - Alpha Base on Easy difficulty. Then when u start immediately turn on the skulls Fog, Sickness, Rebel Supporter, Rebel Sympathizer, and Rebel Leader (U have to find the skulls on other missions before u can use them). Then just simply play through the mission as fast as u can and without losing many units and killing most of the enemy units (Which shouldn't be that hard on easy difficulty). And then once u get the gold medal u will unlock 'Own Worst Enemy'. Oh, and getting the skull and black box on the level will help u get a gold medal.

With the debuff skulls on your score increases greatly. If that is too hard (which it shouldn't be at all) you can still have some help full skulls on. Pain train (units train faster) and bountiful harvest (receive resources faster) can make a big difference.

I chose to do this on the first mission,for some reason i was struggling on EASY so i did it on NORMAL with the skulls mentioned above-Fog,Sickness,Sympathiser,Leader and Supporter and just went through with no tactic apart from speed and to kill the hundred grunts,ramming them is not necessary,just try to make sure that you kill them and they dont die from say,a secondary explosion or something,and i got the achy with a score of 29752,Gold is 27000+
Hope this is helpful,gud luk =]
I think speed is the key.