Resident Evil 6

In order to gain this achievement you will need to get all four Serpent Emblems in any three levels.

Since you might be going for all serpent Emblems this will come through normal game play.

Note: This achievement will only unlock once you go to the special features option on the menu and go into the collection part.

NOTE 2: These listed below are the ones that you might need to make certain character choices to be able to obtain.
Chris and Piers.
Chapter 2 Emblem 2 Piers only
Chapter 4 Emblem 4 (Can be gotten by both characters but Piers is easier)
Chapter 5 Emblem 1 Chris only

Jake and Sherry.
Chapter 1 Emblem 3 (Can be gotten by both characters but Sherry is easier)
Chapter 3 Emblem 1 Jake only
Chapter 4 Emblem 1 Sherry only

I'll post a video linking all the Serpent Emblems for you

The timeline
0.00 Leon and Helena campaign starts
5.52 Chris and Piers campaign starts
11.17 Jake and Sherrys campaign starts
17.31 Ada and Agents campaign starts

This is not my video nor do I own it.
This video was uploaded by XCV //