This is awarded for clearing the Mr. Tomassi
mission (beating Tomassi for a second time).*Edit*
I just saw that Mortifervs
has added a separate solution that covers getting to the mission in the first place (thanks). So I'm adding here to improve the guide:
1) Mission to defeat Mr. Tomassi (again), becomes available during Finnish Tango main story mission.
2) To get it, talk to Emily Pope in Board Room / Central Executive.
3) Get to Turntable / Containment.
4) Room with Mr. Tomassi is on your left, when you first enter Turntable.
5) Kill Mr. Tomassi.
6) To get achievement and skill points, talk to Emily Pope again.
Here's how to beat the mission:Mods
I left this achievement until last so I had the best mods available. I equipped three health boost mods (two level 4 and one level 5). Weapon
I only used Pierce when attacking Tomassi, with rate of fire, reload speed and damage mods. Shatter is a good back up weapon for the other enemies.Hiding spot
There's a great hiding spot under the walkway on the right hand side, in a little alcove. Tomassi can't hit you from here but you can hit him. From here, it becomes a lot easier to manage the other enemies, and you'll be able to gather health drops fairly easily. When the Hiss Distorted (invisible shrieking things) show up, make sure you kill them as soon as possible.Bonus tip - bring a healer
In the Turntable room before you go into Sterling Awe, a Hiss Cluster sometimes
spawns. If it does, knock its health down but don't kill it. Seize it and it'll be able to follow you into the boss fight and heal you as long as it stays alive.
I found this by far the hardest achievement. It's a horrible, frustrating fight and took me about 20 tries...good luck