20 Brewing skill for a start :) Also a Flask of Bloodwater, Deadbone Barley, A Giant Blood Sac and a Bottle. At least according to Prima' Strategy Guide you do. And it's been wrong before (claims Track Corpse is a lvl 20 Wiz spell)
In case you're having trouble finding the ingredients: Flask of Bloodwater; sold by Lybar in West Cabilis, Klok Roshin in the Swamp of No Hope, and various other merchants just outside Cabilis.
Bottle: sold by Klok Sass and Klok Poklon in East Cabilis
Deadbone Barley: Foraged in the Field of Bone (randomly, you'll have to forage several times to get it)
Giant Blood Sac: Dropped by giant swamp leeches in the Swamp of No Hope. Ablut 1 in every three will have one; it's a no-drop item.
I'm sitting in the Cabilis East dungeon at 860 -810 -100, at the bottom of a staircase where new mob spawn at a static location about every 30 sec. Every once on a while (maybe once every 2-10 min) a giant blood leech will spawn with the blood sacs. No running around like a chicken with your head cut off looking for one.