If you’d like to get the Winter Veil achievement but haven’t started the Skyguard/Ogri’la rep grind yet, good news: you don’t have to in order to get Fa-la-la-la-Ogri'la. You can go straight to Ogri’la and start a very brief chain there to open up “Bomb Them Again”, which is the quest you need for the achievement.

• At Ogri’la, pick up “The Crystals” from Chu’a'lor. (Gather 5 Apexis Shards and return to Chu’a'lor. Skip the follow-up.)
• Still at Ogri’la, pick up “Our Boy Wants To Be A Skyguard” from Torkus. (Gather 10 Shards, go to the Forge Camp to the south and trade them for an Unstable Flask of the Beast, return to Torkus. Don’t get the follow-up.)
• Still at Ogri’la, pick up “The Skyguard Outpost from Chu’a'lor. (Report to Sky Commander Keller at the Skyguard Outpost.)
• At the Skyguard Outpost, pick up “Bombing Run” from Sky Sergeant Vanderlip. (Use the provided bombs to destroy 15 stacks of Fel Cannonballs at the Forge Camps to the north or south, then return to Vanderlip.)
• At the Skyguard Outpost, pick up “Bomb Them Again” from Sky Sergeant Vanderlip. (Use the provided bombs to destroy 15 more cannonball stacks.) This is the quest you need for the achievement. The only time you need to have the Holly buff is when you are turning the quest in! There is no need to have it on when you pick the quest up or while you’re doing the bombing run itself.

Hope that’s helpful! My Death Knight went from never having set foot in Blade’s Edge to having the achievement in about half an hour this morning, and most of that was grinding for Apexis Shards.