This quest is not available in game.
Fill the Coated Cerulean Vial at the orange crystal pool in Maraudon.
Use the Filled Cerulean Vial on the Vylestem Vines to force the corrupted Noxxious Scion to emerge.
Heal 8 plants by killing these Noxxious Scion, then return to Talendria in Nijel's Point.
A satyr known as Vyletongue has corrupted the caverns of Maraudon, stunting the growth of many of the plants inside.
Take this vial, <name>. Fill it at the corrupted orange pool found inside the caverns; the coating inside the vial will counter the toxins, turning it into a healing agent.
Find the Vylestem vines inside the orange caverns, and use the purified liquid on them. The corruption will be purged from the plant, but do know that Vyletongue will still control it. He may use it against you...