1. Collectibles
1.1. All Collectible Locations
1.2. All Optional Conversations

2. Story-Related
2.1. Brick Master (Mallrats)
2.2. Nobody’s Perfect (Fun and Games)
2.3. Angel Knives (Fun and Games)
2.4. Skillz (Fun and Games)

Picked Clean
All Left Behind collectibles found
There are a total of 14 artifact collectibles in The Last of Us: Left Behind DLC. Finding all of them will earn you the “Picked Clean” bronze trophy. Three collectibles are obtained automatically while playing through the story (cannot be missed). Only eleven need to be located manually.
If you miss a collectible, you can still get it via chapter select. The collectibles you have already found are listed under “Bonuses” – “Collectibles” in the main menu.
Chapter select provides an additional overview of how many artifacts you have found in each chapter.

BFFs
All optional conversations found in Left Behind
There are a total of 20 optional conversations in The Last of Us: Left Behind DLC. Finding all of them will earn you the BFFs bronze trophy.
You do not have to get all of them in one playthrough! If you miss one, you can get it via chapter select and still earn the trophy. Unfortunately, the game does not provide any statistics about the conversations. So you must figure out on your own which ones you are missing — there is no in-game overview for that.
Only two chapters (chapter 2 & 4) have optional conversations. It will just take a couple of minutes to get them all, because they are right next to each other. Eight of the conversations are with the same fortune teller and you just need to keep pressing triangle over and over again.

Brick Master
Win the brick throwing contest
Chapter: Mallrats
The brick throwing contest is triggered automatically after going through the halloween shop where you put on a mask. You have to throw bricks in order to destroy all 7 windows of the red car, but you need to be quicker than your friend. By holding down L1 you can aim more precisely on long distances.

Nobody’s Perfect
Played Jak X Combat Racing
Chapter: Fun and Games
In the very beginning of this chapter you will see a carousel. Go up the stairs on the right and you will come to “Raja’s Arcade”. In the back of the Arcade is a racing seat. Press triangle to hop on it and wait until Ellie is done playing. Just keep watching Ellie until the trophy unlocks.

Angel Knives
Defeat Black Fang without getting hit
Chapter: Fun and Games
In the very beginning of this chapter you will see a carousel. Go up the stairs on the right and you will come to “Raja’s Arcade”. Here you will find a broken arcade machine that you have to interact with. For this trophy you must complete all button combinations without failing a single one. You only have a very limited time frame to press the right buttons, so you gotta be quick. If you do fail a combination, simply restart the encounter.

Skillz
Win the water gun fight
Chapter: Fun and Games
A couple of minutes into this chapter, you will have to compete against Riley in a water gun fight. You have to win 2 out of 3 rounds to earn this trophy. The little introduction part in the beginning doesn’t count. Only the rounds where the first hit wins.
Riley will hide somewhere in the shopping center. You should run around to draw her out. If you run fast (hold down L2) she will rarely hit you. Try to move from cover to cover as you circle the area. Also turn up your speakers to hear Riley more easily. If you listen carefully, you can hear from which direction the noise is coming.