Agents of Mayhem

Contract Killer contracts are obtained via as a reward on the Giant Map and sometimes through Lairs. To get it through the giant map which is located on the ark which is unlocked half way through the game. You will need info *or the files you get from killing enemies, treasure, or reward from a mission* So many of them are needed to unlock and a timer will go off for a certain amount of time. In turn you may get a contract. The contract is mostly individualized to certain characters. Some are general. Contract Killer and Contract Thriller do not cross over or work together.

For Contract Thriller....
Each day there is 3 new contracts available to do. Complete 15 to get this achievement. Here is some tips. I recommend first to just complete the game so you can repeat missions it will make it easier. Up to 6 players per team. Can be setup public or private.

Clear Legion Alert X amount of times (change to level 0) go to the map look for (Acquire Vehicle for Quartermile) jump into the car and then jump out right away. Your mayhem meter on the right corner will be up 2. Continue killing the enemies with what I recommend Hollywood, Scheherazade, and Fortune.

Killing an assortment of enemies- Well depending on the enemy will depend on the mission you want to repeat. Sleeping Giant, Bubble Bubble, Toil and.. has a great assortment of enemies. Bubble Bubble also has those bombs that chase you (can't think of it at the moment)

Fine Aim Melee Kills, Critical Kills, Special Kills, Mayhem Mode and General Kills. I repeat the Star Power mission All The Rave. Get to the part where you see the dancers and just start killing. Using Rama you can get the fine kills. Scheherazade especially if she is in Mayhem mode you can get melee kills and Mayhem kills at once. Again Hollywood for Special since his recharges fast and causes the most damage.

To get the money or supply missions make sure to max out Fortunes ability for companions to get extra 50% money. Joule 50% R + D Materials. You can get extra the more difficult you make the game as well

Treasure chests are pretty easy to come by just run around the map or raid a legion lair

Legion Lairs can either be obtained via the big map, finding one randomly or better yet doing a mission (which all basically have lairs).

Golems, Ice Barrage , Fracking Devices are random I say just do little missions around the main map until one pops but it won't start happening until you get at least half way through the story arc.

Gremlin Tech- If you go into the pause menu where you see squad, ark, missions city map, inventory, Click on Inventory. My favorite item to use is the Gutterball Gun. Not only is it the fastest to cooldown but it is also the cheapest to make.

World Legion Lair- The reason you see only 1 is because you have to completely clear the world map to get to the lair once beaten this will be complete.

Some challenges are easier then others and some you will not beat. Good news is if for some reason people stop playing at least 1 challenge a day it seems you can easily do it yourself. ^_^ Might take longer but it can be done. Will add more information if I am missing a mission or they add some.

"When sending your agents in the different regions of the Global Conflict , you will sometimes obtain contracts. This is the map where you can only access while you are at the ARK.
You can buy the (Frugal Calendar App) in the Requisitions area to get 3 contracts instead of 1. You can sometime get these contracts from opening chests.

You can see your available contracts in your mission menu under "Contracts". On the top part, there are The "daily connected contracts", which don't count toward this trophy. Below these "daily contract", you will see many square icon representing the contracts you want for this achievement. They are listed under the word "Active". After playing for awhile, you will stack up many of them.

Some contracts are easier than other, some of them need to be done with a certain agent while others can be done with anyone. Don't worry too much about the hard/grindy contracts and try to complete the easy ones while you're normally playing. You will get many easy contracts if you always send your agents when you can, and will be able to do them without worrying too much about it."

Credit goes to Ashbo82, the original writer of this solution.

Note: If you attempt to 100% this game, this achievement will most likely come naturally. I did not attempt this achievement at all during my playthrough and I got it while grinding to have all my agents gotten to level 20. The most annoying one is the "daily connect contract" for a different achievement called Contract Thriller.
You can see how many contract in total you have completed by checking your Stats in your achievement section. Press Home button; go to Achievement tab; go to "See all my achievements"; go "Progress" tab, scroll down a bit and press left to choose "stats".
Here is where you find out about the number of time you play, cash you earned, chests opened, Legion killed, etc.