HITMAN

This will take multiple play throughs or saves...

KILL MANDOLA WITH THE CRYSTAL BALL -
Follow the fortune teller mission. To get the fortune teller costume, next to the shop is a switch the turn the lights off. Wait until the woman checking her phone walks away before hitting the switch. The fortune teller will then come out to check it. Choke him. There is a box to hide him in next to the switch.
You then need to get rid of the previous customer. Sit down at the chair, and wait til he finishes talking to tell him to leave.
If you decide to kill him, make sure to turn up the fog machine next to the door first, or you'll be spotted.
Once he's gone, find your target. Talk to him, and escort him back to the shop. Sit down.
Again, before you kill him, make sure the fog machine is turned up.
Kill him.

ELECTROCUTE KONG - UPDATE FROM LOTS A LOUD...
"To electrocute Kong you have make the reflection pool overflow and then shoot down the star into the water"

Follow the Gone Shopping mission to get the key, or pick the lock into the back of cafe. Use the waiter costume in the locker and exit into party. Behind the bar is a button to make the water in the pool rise. Be careful as 2 of the waiters will see through your disguise.
When the target stands next to the pool, shoot the star in the middle. It will drop into the pool, and Kong will be fried.

*EDITED* Thanks to Radic0n...

For the electrocution, you can climb a pipe in the toilet of the shisha cafe to release the star from a winch, so you don't have to shoot and risk getting noticed.

POISON THEM BOTH WITH ONE PIPE -
Make sure you have equipped the lethal poison for this.
Follow the Waiting for the Man mission, to get a body guard costume. Find the target, talk to him, and lead him to the meeting point. He will say he doesn't need you when he gets to the stairs. Quickly run upstairs, and find the pipe. You'll be told that you've found the meeting point when you get to it. There is a guard there that will see through your disguise. Distract him with a coin (I threw it while behind him, and he went downstairs). Poison the pipe.
Once Mendola is upstairs, Kong will make his way to the meeting. His body guard will see through your disguise.
When they exchange their illegal activities, Kong will suggest they celebrate with a smoke.
And they die!

*EDITED* Thanks to Radic0n...

For the pipe poison, you don't necessarily need to equip lethal poison before you enter the mission, there's a lethal poison pill jar on a table down the stairs of the southern shopfront below the meet-up point.

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This is done in the Marrakesh summer bonus mission. You will need to kill Mendola with a crystal ball, by acquiring the fortune teller's disguise. You will need to electrocute Kong, by acquiring a security and waiter disguise, as well as a key to the backdoor area of the cafe. Finally, you will need to poison both of them on a pipe. Lethal poison can be taken in your loadout and is unlocked by reaching level 10 mastery on Sapienza.

Here is a video guide with English commentary for this achievement!


Here is a playlist of guides for this game!

https://www.youtube.com/playlist?list=PL-HeW6XkKdUK9Qh-6TvL3...