Potion Of Nyad's Kiss

Level: 20-21
Weight: 1
Type: Quaff
Effect: Water Breathing, Cure Light x2
Area: Elven Foothills
Mob: None (on the ground).

Port Baron Sarph, go 3e, u, w, s, u, n, look around for Half-Elven Rogue and kill it to get Key To Sarphyre's Display.
Then go back to Baron Sarphyre and go 2e, 2n to get to the case, open it with the key and get the Fae Warding Glyph from it.

Then port Nyad or go 2s, e, u, w, s, u, s, d, 2s to get to Nyad, give her the Glyph and you will be transported to a room which has the Nyad's Kiss on the ground. You may as well Grab the Nyad Hair while you're here and complete the Gargoyle Bracer Quest while you're here.

The Wreath of Water Lillies can be given to Nyad as well, and this is technically part of this quest too. However, it will not directly help you complete it.