There are a slew of achievements/trophies to get through Dragon Age 2 on just the first run through and for the few that are left over, assuming you have an Origins save file, you can wrangle them up in no time with a second partial playthrough. There are plenty that require collecting multiple items and codex entries that change places through the different acts of the game so make sure you revisit the same places over and over as new objects appear over the course of the game. So with those words of wisdom, set a course for Kirkwall and start your collecting!
Side with the mages 5 time.
During the course of the game, you will be given the option to choose the mages side or the Templars side numerous times. It is impossible to get both on one playthrough, so pick a side and stick with it. Continue to side with that group until you receive your achievement/trophy.
In Act 1, the missions that affect the outcome are “Wayward Son” found in Lowtown, “Act of Mercy” in Gamlen’s House, and “Enemies Among Us” in Hightown. The others begin from “Showdown” which is at the beginning of Act 3 and will lead to the missions “Night Terrors”, ”Best Served Cold” and “On The Loose” which can be found from letters on Hawkes desk. If you side with the Mages 5 times, you will receive the Arcane Defender reward. Side with the Templars 5 times and Mage Hunter is yours.
During each year in Kirkwall, discover 3 secret messages from the band of three.
To get this, you will need to find 3 of the 4 codex entries that are marked “The Enigma of Kirkwall” in each chapter. In Act 1 they are found in The Gallows, TheViscount’s Keep, The Bone Pit, and Lowtown at night. In Act 2, they can be found in the Chantry, The Docks, Darktown, and the Gallows Dungeon during the “Dissent” quest. In Act 3 you can find them in “Gamlen’s Greatest Treasure” quest, on the Docks during “The Last Straw,” and there are two that can be found during the quest “Justice.”
A Friend in Need
Upgraded the armor of one of your party members.
This can be done by purchasing armor upgrades from around the city or can be done by competing the “Birthright” quest near the start of the game by visiting Gamlen’s hovel.
A Worthy Rival
Earned the Arishok’s respect.
You will need to get the Arishok’s respect before finishing the quest “Demands of the Qun.” This can be done by agreeing with the Arishok in his dialogues while speaking to you and Avaline at his throne, as well as choosing to tell the Arishok about his dead men during the quest “Offered and Lost.”
Kicked the slavers out of your ancestral home.
Complete the “Birthright” quest and you will receive this.
Champion of Kirkwall
Complete Dragon Age 2.
Simple enough. Finish the game and these measly 20 points/Silver Trophy is yours.