Risk: Factions

Also an easy and perhaps simpeler method is:

Start a game with two controllers. Choose a 2-player game in world conquest mode. Pick the ''proving ground'' map.

Make sure you have the attack die as available objective and get that objective with the first ''achievement''-controller.

Then save up all the troops for both controllers. Then distribute around 50 troops per region for the second controller. As soon as you have about 5 or 6 areas with 50 troops each with the second controller you should have saved up about 250/300 troops in one area for the first controller.

All you have to do is go fast-attack (X) with the first controller. Using fast-attack you can see by the way the numbers go down if you've got a super overkill. For example, when you attack and the number goes from 38 immediately to 0 you super overkilled the opponent.

I got the achievement in 3 games doing the above with 12 super overkills. As for troop collecting, try to divide the land so both controllers get enough troops and also try to attack one area back and forth so they both keep getting stars to trade in.

good luck!

Ramon's solution works, but I thought I'd improve upon it some. The problem with his solution isn't that it doesn't work, it's just it takes so darn long to accumulate troops! So instead of fighting on "Proving Ground", pick a Custom Match. Like Ramon, choose World Domination, but instead choose a 3 person match, and choose the Classic Risk map. Now you'll have 1 AI player, but using two controllers, you'll kill him in one round, if not two. As long as the AI doesn't take any important objectives (the only important ones are Attack Die, Guaranteed Card, and maybe 2 Troops, though with this strategy, 2 Troops extra troops per round isn't going to matter much), you'll end up playing against yourself on a huge map.

As like the rest of the strategies, make sure the second controller gets Guaranteed Card and 2 Troops, and you MUST GET Attack Die. As for Defense Die, I gave that to myself, since I thought having the second controller get it would just hurt my troop numbers too much.

For my game, I made sure the second controller owned the majority of the continents. This allowed them to amount around 30-40 troops per round. I was only gaining 10-20 a round, but with the Attack Die, I wasn't losing 50 troops every battle like the second controller was. I fought most my battles on South America. I owned North America and my second controller owned the rest.

Other than that, Ramon's strategy was dead on. 50 troops per region for the second controller and stay above 200 on yours.

I also experimented with the Airfield but IT DOES NOT HELP! In fact, all it does is burn through the second controllers troops quicker. The Airfield adds +1 to your highest roll, it doesn't actually change the die roll. So rolling a 5 does not actually make it a 6. You still rolled a 5. And for this achievement, you need to roll three 6's. So save yourself some grief and leave the airfields alone.

Please either comment below or send me a Personal Message if you have any comments or improvements.

In order to get this achievement I set up a game as per Ramon's initial suggestion. But after reading some comments about the probability of this achievement I thought I'd try and explain it...

Image 1: The Setup: Custom Game > 2 Player > Proving Grounds


Basically the Attack Dice is the key to speeding this achievement up. (3.5x) Take the objective that gives you the Attack Dice first, and then make sure the defending army has 3 continents, and the attacking 2. This gives troop rewards allowing you to build your armies quickly. Trade in your stars after you obtain this for additional troops. I found it quicker just to keep taking your troops and maneuvering without attacking, than it was to attack each other for star rewards. It took approximately 1 hour to set this up.

Image 2: Explanation of How Many Troops are needed and why;
[Click for a Slightly Higher Resolution]

Remember probability implies what happens on average! - The numbers stated in my calculations will not guarantee a Super Overkill, as it is a game of chance, but on Average, with these numbers the average person would get 10 Super Overkills in one game.

The Setup I had in image one yielded 8 Super Overkills by the time I had fast battled my way through all the defending troops. (Probability suggests I was slightly luckier than average).

Hope it helps, let me know if somethings not clear.

Ramon's strategy seems to be the most reliable but some things need to be addressed. Using two controllers on a two player custom game works great.

First of all, the achievement controller must keep all of it's soldiers on one territory and attack the groups of 50's. If you take you large group and attack another large group, the best you can get is ONE super overkill since all of the remaining enemy soldiers will be destroyed. While on the other hand, each group of 50 will give you a chance at a super overkill. I've got one as soon as 48 remaining and as close as 14 remaining.

Second, having the missile and the attack dice together doesn't help becuase you can only roll four dice at once, not five. The game will just alternate between rolling the missile dice and the attack die dice. Though I think having an airfield will help your chances becuase it adds plus one to the top dice.

Third, I would recommend drafting as many troops as you can stand, it is pretty boring. Have one controller with the free card bonus and the other controller with the +2 bonus that way each can get extra troops. If you want more objective bonuses without winning the game, just have the second controller capture the achievement controller's HQ that way you can have as many bonuses as you want and still won't win until you take back your HQ. When I did it, I built up 500 for the achievement controller and 8 groups of 50 for the second controller then I fast-attacked each one. I more or less got one super overkill every two groups of 50. It is random, so you could get one with every group or 50 or none at all. It may take several tries, that is why I suggest doing it all in one very big game since setting everything up takes longer than making another group of 50. Don't finish the game until you get the achievement.

Easy way to get this acheivement:

Command Room, Normal Game, 3 players, any map (I choose Classic Risk).

Make sure you have an objective that has the Attack Die.

Place you capital where the computer players can easily capture it, and allow them to. Your first objective is to get the Attack Die, and to build a small strong hold (such as Australia or South America on Classic).

Once you have the Attack Die, capture and control both enemy capitals. This will insure that no one can win, unless some one dominates the board.

Now just keep attacking with your 4 dice until you get 10 lucky rolls of 6-6-6.

Edit: Forgot to add that you can Hit 'X' to Fast Attack, and it still counts.

Simple Solution:

Roll 3 "sixes" 10 times during an attack. Opposition must have 5 or lower on each die. You know you have done a super overkill when the enemy troop number instantly drops to 0 (e.g. 10 to 0 immediately). Counts whether you watch the dice roll or you fast attack.

Other solutions listed here are all the same. Using 2 controllers, spread out "dummy" profile troops across map to have something like 50 units per location. Put all your units in the same location. Fast attack across each enemy location once you get around 300 troops, which effectively rolls 3 dice for you over and over.

Doesn't take long to setup (far less than the hour stated in other solutions).

Don't worry about all the talk of having the attack die, airfields etc. This only increases your chances slightly, and isn't worth the messing around of trying to make use of this.

In 2 attempts at setting this up I received 4-5 super overkills. I already have 6 from playing the game previously, and this was the last achievement I needed.

There is no point in trying for this achievement until you have done everything else, as you may get a few along the way.

I believe that the above explanations are over-complicated. I earned the achievement in the campaign mode, but instead of getting the 3 objectives and moving on to the next campaign, I played each campaign until I eliminated all other opponents, resulting in higher troop counts, and more importantly, more dice rolls. Statistically, you will roll 3 sixes once every 216 opportunities, meaning you need approx. 2160 attacks with 3 or more attackers to get this achievement. It is just the law of averages