Unleash the power of love contained within a holiday necklace.
Any of the necklaces from Love is in the Air will work for this achievement. They all drop from Apothecary Hummel and any of them can be used by any player since it is a necklace. Now you have a reason to roll for the item instead of passing on it every time! (Of course, there was that one time in Cataclysm where the necklaces could be disenchanted. Very, very nice way to farm for shards. Blizzard fixed that relatively quick, though, haha.)
Listed for your convenience:
The use effect causes you to launch a rocket that explodes into two pink hearts.