This is a single-part quest that was introduced in the 1.10 patch; the NPC is in Cenarion Hold, inside the inn, to the left of the innkeeper. As said in the quest text, you need to gather two venom sacs: one from Kurinnaxx, first boss in AQ20, and one from Venoxis, the easiest boss in ZG.

Kurinnaxx is not hard, but if you don't know what to expect, he will give you a bit of trouble. Everybody in the raid needs to keep moving around to avoid sand traps; if the damage they inflict isn't much, and can be resisted (and absorbed with nature protection potions), the main issue is the silence effect, definitely a problem for casters (can't cast anything), and even warriors (you can't taunt or shout when silenced). Tanks will get tagged by him, the debuff increases damage taken and it stacks; it's crucial that when one tank has 5 or 6 debuffs, another tank picks him up until the former tank has lost the debuffs (30 seconds or so). So, warriors taunt and keep Kurinnaxx moving around to avoid sandtraps, and share the job as debuffs rain on them, melee DPS keeps moving along and burn him down. Avoid standing -behind- him at all cost, his tail does a very nasty cleave, hit his sides instead; don't stand infront of him if you're not a warrior, his frontal attack is even worse. Kurinnaxx isn't hard, and you don't need epic gear to win this, it's just basic group coordination and communication.

Venoxis is the easiest boss in ZG, found on the south side of the instance past the nook where the bat boss/Jek'lik is (ZG is all nooks, there's no order in which you kill the bosses). 4 serpent adds, one priest that turns into a big snake. Have mages sheep and/or druids sleep 3 of the adds, the main tank picks up Venoxis and drags him to a corner; secondary tank picks up the non-sheeped/sleeped snake, everybody kills it, repeat with the 3 other adds. When all 4 adds are dead (they're easy), everybody moves on to the main tank and help him burn down Venoxis; the only real hassle with Venoxis is the poison clouds he spreads around (acid green clouds, hard to miss them), they hurt a lot if you stand in them. The main tank will need to move Venoxis out of those clouds, melee follows out and keep burning the big snake down. And that's pretty much it, hence why Venoxis is called the easiest boss in ZG (if you want a real fight, head over to Jin'do lol).

Despite being a raid quest, this quest count towards the Loremaster achivement.

Soloed as 80 prot pala, with mostly quest and BS blues. Kited Kurinnaxx around, healed when debuff was at 1-2 stacks. Venoxis was pretty much tank and spank, slowly walk around to avoid the poison clouds.