Dragon Age: Origins

You can get this and "Magic Sympathizer" with a minimal amount of replay (just one or two dialogues) if you delay the moment of decision as long as possible.

When you enter the mage's circle tower and meet Wynne, side with her and get her to join your party. Then play through until you free First Enchanter Irving. He will give you the choice to proceed back down to the Templars or wait, choose wait and then save your game.

To get "Annulment Invoker," when you talk to the Greagor, tell them you cannot afford for a single blood mage to be left. Stick to the side of paranoia. You do not have to have Irving killed; he will voluntarily break the circle if you continue this course of conversation.The achievement will unlock as soon as you finish your conversation with Greagor.

If you haven't gotten "Magic Sympathizer" by this point, re-load the game from your save and follow the instructions I left for that achievement.

Please note that by siding with the templars and sticking to that course of action, once you go to Orzimmar there is a quest in Dusttown(Precious Metals) that has you purchase Lyrium out of pocket(40-50G, depending on persuasion) that you must sell to a mage named Godwin in the Circle Tower(guy hiding in the closet). By siding with the templars, all the mages will be gone including Godwin and you will not be able to complete the quest as well as being out the gold. Though upon returning to the dwarf you buy the Lyrium from, you fight him and he drops 20G. The Lyrium can also be sold for 12.5G, so all is not completely lost.

Once you reach the Circle Tower, you'll have to fight your way up it. When you get to the top, you'll have to retrieve the Litany of Adrella. You'll go into another dimension called the fade where you'll collect various abilities and fight various demons. Then you'll fight the Sloth Demon. He has several phases. Just keep control of your party and you should win the fight. Make sure you use your main characters magical abilities. I'd highly recommend the Spirit form as it has the ability to cast a highly damaging freeze spell. After this, you'll wake up and will be given the Litany of Adrella. Now you should head into the Harrowing Chamber. There an evil mage named Uldred will be holding the other mages under captivity. After some dialogue, a fight will begin. Make sure to use the Litany of Adrella to prevent the mages from turning into Darkspawn. Whenever a pale yellow circle appears under them, use the litany. Now, when Irving talks to you, choose to wait and do some exploration. Now, save your game. When you decide to head back down, you'll meet Greagor, the Templar leader. For this achievement, tell him that you cannot afford for a single blood mage to be left. You'll then side with the Templars and once the conversation is over the achievement will unlock. Then, reload your save, go back down and tell him that the circle is back in order. Through the rest of the dialogue, you'll end up supporting the Mages and Greagor will guarantee that they will stand by you during the final battle. After another talk with Irving, you'll unlock the following achievement: