This quest is given by Siege Master Stouthandle if you're Alliance and Siegesmith Stronghoof if you're Horde, but unlike similar daily quests, these are turned in to your faction's Commanders -- the ones that ask you to slay 20 opponents -- instead of the original quest givers. I'm not a big fan of this quest because the Cauldron of Flames in Southeastern Wintergrasp, where the fire elementals who drop the quest item Eternal Embers can be found, is a heavily farmed place.
On a good note, the Flame Revenants are guaranteed to drop 1-3 Crystallized Fire, so it's not bad money at all if you decide to do it when your faction controls Wintergrasp. Otherwise, when Patch 3.0.8 kicks in, it's easy enough to complete the quest when killing players elsewhere in the zone so you won't have to compete with Crystallized Fire farmers. Completing the quest rewards three Stone Keeper's Shards, 13 Gold 23 Silver, and 1241 Honor at Level 80.
Warding the Warriors (A) / Jinxing the Walls (H)
The last random daily elemental farming quest is one that requires players to kill water elementals in the Glacial Falls in East Wintergrasp. Because Water Revenants have a chance to drop up to two Imbued Horde Armor or Enchanted Alliance Breastplates, it's best to do these quests when your faction controls the zone as with Bones and Arrows and Fueling the Demolishers. Sorceress Kaylana gives this to the Alliance, while Hoodoo Master Fu'jin gives this to the Horde. Completing the quest rewards three Stone Keeper's Shards, 13 Gold 23 Silver, and 1241 Honor at Level 80.
Stop the Siege (A / H) or Defend the Siege (A / H)
The last daily quest is only random depending on whether you get it while you control Wintergrasp or are assaulting it. If you control the zone, you will get Stop the Siege from Senior Demolitionist Legoso if you're Alliance or Alterac Valley favorite Lieutenant Murp if you're Horde. If you don't control the zone, they will give Defend the Siege instead. However, you can complete the quest whether you are attacking or defending.
Stop the Siege is the more straightforward of the two quests, requiring you to destroy three siege vehicles. This is easy enough to do and it will help if you are in a raid group. Defending the Siege is easier to do on offense, as you will get credit for the quest whenever a siege vehicle destroys a structure. This means if there are three siege vehicles within the vicinity when a wall or tower is destroyed, this quest easily completes. On offense, you'll have to accompany vehicles to destroy workshops or Southern towers, which isn't always done. Completing the quest rewards three Stone Keeper's Shards, 13 Gold 23 Silver, and 1241 Honor at Level 80.
Completing all Wintergrasp daily quests available reward up to 10 Stone Keeper's Shards (9 at the moment as Victory for Wintergrasp seems to be unavailable) and almost 5,000 Honor, which is an awesome haul considering players can do it solo. It's curious to note that the quest NPCs will despawn for a short while when the battle begins or sometimes even for the entire duration of the battle. The Victory for Wintergrasp quest also seemed to occupy or share the daily Battleground quest slot such that it became unavailable if you already accepted a daily Battleground quest. Hopefully the quest bugs will be fixed soon.