The Siren's Tear is sold by the Ahlurglgr <Clam Vendor> in Borean Tundra for 100 [Winterfin Clam]. It has a very small chance to be contained in Darkwater Clam and Giant Darkwater Clam. It can also be found within a [Bag of Fishing Treasures], which are rewarded from the fishing dailies Marcia Chase offer in Dalaran.
Siren's Tear as an ingredient
Tailoring recipes using Siren's Tear
| 420 || [Deathchill Cloak] || 5 [Bolt of Imbued Frostweave], 6 [Eternal Fire], 4 [Eternal Shadow], 1 [Siren's Tear], 1 [Frozen Orb] || None || Trainer, Loremaster of Northrend
| 420 || [Wispcloak] || 5 [Bolt of Imbued Frostweave], 6 [Eternal Life], 4 [Eternal Water], 1 [Siren's Tear], 1 [Frozen Orb] || None || Trainer, Northrend Dungeonmaster
1 Siren's Tear will be buyable about 2 to 3 hours after both [Northsea Pearl] are bought. (Both can appear on Ahlurglgr's inventory at the same time.)