Ghoulic Viper Fang -- Kill Task  

In order for these kill tasks to work properly for you, you must be within the level range of the task. This can be found by delving the info of the kill task item in question. This will also give you the name of the person to whom you must turn said item in. You also are limited to twenty (20) of any particular item. At the higher levels, 45-49 or so, each stack of 20 items will yield approximately 2 bubbles worth of experience total. Many of these items are found in the frontiers, so expect a random gank here and there while farming. Sucks, but there it is.

If you are refused when you try to turn one in, check to make sure it's not an item you've already turned in 20 of, and that you fall within the level parameters. These are really a great thing to have saved up for when your toon hits 47 and you want to get to 50 in an hour. Yeah, takes an hour because you have to hand them in one at a time. Lotta de-stacking going on.