Champion of the Naaru IS still attainable
This definitely does not work for every one. You say you had completed the old SSC attunement quest, that's the key point here. The new one if you were to pick it up today, will not work for this, also you still need to be level 70 to pick it up (which I still feel raw about).
I have completed the SSC attunement on new 70's since wrath went live, mostly because one of my 70's is a 70 "RP" toon, who I only run level 70 instances on and was doing kara/gruul's anyways, so why not do the SSC attunement, and on other toons for funzies.
When I then completed the Tempest Keep attunement on them, I did not recieve any title, nor was I expected to, as the quests have new Quest ID's, ones that do not count as credit towards COTN.
I had a friend do pretty much the same as you, she had done the SSC part when current, and only had to kill Magtheridon left to do, she didn't get it done prior to the big nerf to TBC bosses though. When in wrath we she picked up Trial of Strength: Magtheridon, after abandoning it (since at this point attunements weren't mandatory anymore), she did not get the title.
Are you sure you picked up the Magtheridon quest again, haha.
I've had friends who still had it in their quest logs, in wrath (some as late as 3.3) and one in cata (4.2) who got their titles when they completed it after having it in their log all that time, yet the friend who picked up the new version (post 3.0.8) did not get the title.
Anyways, the key point here, is you completed, at least the old version of the SSC part for the title. Doing the quests in heroic slave pens, now, do not give credit towards the title. Or at least have not for me on the various toons I've tried it on.
I just wish that they would "fix" the SSC attunement part. Apparently you can only pick up the quest at level 70. being 71 or higher makes you ineligable for it. You can share the quests sure, but only with other level 70s who have also completed The Mark of Vashj. But since you need to be level 70 to pick that one up as well, it makes it hard for a level 71 or higher to have done that quest. Unless they for whatever reason happened to, at level 70, find themselves in Heroic Slave Pens, did the quest (which is just talk to the NPC, the quest auto completes when you talk to him), then thought screw doing this second quest, it's a raid quest.
Just yesterday I completed the Mag part and turned it in. I did not receive any credit upon initial turn in. I then logged out, and logged into my hunter. Then I logged back out of the hunter, and back into my warrior. Upon logging back into the warrior, I was granted the achievement and title. I'm not sure why the logging out and in triggered it, but I have a feeling something is still buggy regarding this chain. I saw another person post on wowhead that they had the same thing happen.
I just turned in my Vials of Eternity quest yesterday as well, and I plan on finishing up the BT part today, to see if I can still get the Hand of A'dal title as well.
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