Dragon Age: Origins
76 Achievements
1,750
75-104h
The Ultimate Sacrifice
The ultimate sacrifice was made in defense of Ferelden Details for this achievement will be revealed once unlocked
50
How to unlock the The Ultimate Sacrifice achievement in Dragon Age: Origins - Definitive Guide
This achievement is tied to one of the different endings. The night before the final battle, when Morrigan confronts you in your bedroom and proposes her "alternative" solution, you must decline. You cannot let her perform the ritual, whether it be with you, Alister, or Loghain.
On a side-note. If you decline her dark ritual, she will leave your party for good.
Later, after beating the archdemon, you will be forced to sacrifice a Grey Warden (you, Alistair, or Loghain) and the resulting ending will net you the achievement.
Just to add something that wasn't mentioned in the other posters solution, if you are playing as a female character and have romanced Alistair do not take him with you if you are trying to get this achievement. The conversation options can make you think you're talking him out of taking the final blow in your place, but he does it anyway. There is no way to prevent him from taking it to save your character if you turned down Morrigan's ritual and take him with you.
Not sure if many people will be trying to get this still but you can also get this even if you take Morrigan's offer.
After you defeat the arch demon a scene will play where, in my case, Alistair will make some statements and ask a few questions. After he was finished talking and before going out the doors to greet the public I saved and loaded the auto save file. As soon as the auto save loaded the achievement popped!
Not sure if this counts towards getting all possible endings but will update when I find out.
*update*
It did count towards getting all four of the endings!
Choose a king for Orzammar, gain the support of the Elves, enlist the Mages and poison the Urn of Sacred Ashes. Then finish up the rest of the story. This time, pick someone to sacrifice during the final battle and don't accept Morrigan's offer. Now sacrifice either that person and you'll unlock the achievement. To get the other ending, simply redo the battle and sacrifice yourself. Now, all you should have is to sacrifice another ally. If you picked Loghain the first time, then simply pick Alistair. Then finish the game and you'll unlock the following achievement:
Note: If you go this route, Morrigan will leave your party.
Note 2: Even if you aren't the one to make the sacrifice (see Perfectionist), then this will unlock.
After "The Landsmeet" ends, travel to Redcliffe. You will find out what the fate of the Grey Wardens is. Morrigan will offer you the chance of going through a dark ritual the night before the battle. Refuse her. Then complete "The Final Battle". There's nothing special to "The Final Battle" other than surviving waves upon waves of Darkspawn.
Once you make your way to the top of Fort Drakon, the fun begins. This isn't quite the same as your other encounters with dragons. The Archdemon is much, much tougher. Plus, you'll have to deal with a few waves of Darkspawn that run out of the Fort. Call in support troops (see Defender for moe details) to help out. There are also several ballistas around the roof. Get behind one, push to rotate it so it's aimed at the Archdemon and fire away. You can basically stand behind the ballista, and pushing when it's ready to fire over and over, only moving away from it when there are Darkspawn near.
One Playthrough Method: After discussing what to do in Redcliffe, make an extra save. In one, refuse Morrigan, complete the game, and then reload. Accept Morrigan's offer.
Note: If you go this route, then Morrigan will leave your party.
After "The Landsmeet" ends, travel to Redcliffe. You will find out what the fate of the Grey Wardens is. Morrigan will offer you the chance of going through a dark ritual the night before the battle. Refuse her. Then complete "The Final Battle". There's nothing special to "The Final Battle" other than surviving waves upon waves of Darkspawn.
Once you make your way to the top of Fort Drakon, the fun begins. This isn't quite the same as your other encounters with dragons. The Archdemon is much, much tougher. Plus, you'll have to deal with a few waves of Darkspawn that run out of the Fort. Call in support troops (see "Defender" for more details) to help out. There are also several balistas around the roof. Get behind one, push to rotate it so it's aimed at the Archdemon and fire away.