A New Day
Tallis joined the party. ("Mark of the Assassin" downloadable content)
You get this at the start after meeting up with Tallis and cleaning up some trash.
Chasing the Game
Lured and killed an alpha wyvern near Chateau Haine. ("Mark of the Assassin" downloadable content)
You have to find and kill an Alpha Wyvern. Which is a boss. For this you have to find all lures.
Evaded vault security in Chateau Haine. ("Mark of the Assassin" downloadable content)
Once you get inside the castle you can sneak around to get to the vault. There are guards however which you must dodge/evade. For this however you must opt to do as Tallis recommend instead of going in like you are some kind of undefeatable hero.
Once you have made your way in there the trophy will trigger. This will happen after the gate switch puzzle. Puzzle may seem confusing, but have both Tallis and Hawke mirror match their movements pretending there is a mirror from 1 door to the other.
Disarmed the fire traps in Chateau Haine's vaults. ("Mark of the Assassin" downloadable content)
This one is easily overlooked. First you have to get into the vault from the Dungeons and then solve the 4 puzzles. 2 are easy but the third can be a true pain the butt. And the last one is pretty tricky unless you know where to look and what to look at.
You can access the vault after you got your team back and escaped prison. Make sure you do not go trough the crack in the wall. Instead go the opposite side for the entry into the vault.
Puzzle 1 & 2: You will a pedestal with a marker in the center. With 2 colors you can take on the side. You can go through the door the color at the ground being the same color you have on you. The Idea is that you get to the end, get 1 color to place it in the center, then go back and through the way towards the other end to get the last color. After this mix the colors to open the last door for a mini boss and a few treasure chests.
Puzzle 3: Picture Perfect! There are 25 tiles face down. You need to turn them all face up. When you select a tile to turn face up all the other tiles that directly touch it will turn as well (imagine a 'plus' shape). And they will turn regardless of how they are facing. So if 2 of the 5 tiles are face up and the rest face down they will all swap so you have 3 face up and 2 face down.
Puzzle 4: You may have noticed after solving each prior puzzle you made a picture visible. There are 15 men in the picture in 3 rows. The same as the tiles in the main room next to entrance of the area with the puzzle you just did. A bunch of them have hats. Turn the tiles in the main room (facing the fire wall in front of you) according to those with the hats. Doing this successfully will close off a piece of the fire surrounding the chest(s).
Once you solve these puzzles the trophy will be yours.
Mark of the Assassin
Defeated Duke Prosper, with or without Tallis. ("Mark of the Assassin" downloadable content)
The only hidden trophy but ironically also unmissable. Regardless if you follow Tallis or not in the caves you will get to this boss. Once you defeat this boss the trophy will be yours.