In the deepest parts of the Morass of Kirkgor there can be found the  Iedir trolls.  They are the twisted descendants of the Aidir, a once noble race of orcs, that were twisted and devolved with the promise of power. They became just as dark and twisted as the power they craved. There are few of them left, for as their mind regressed, they came to attack each other decimating their numbers over the years.
 
Sadly, their great legacy and strong minds, have dulled to the point where they act on basic primal urges of eating and sleep. One of the twisted blessings this dark power has given them over the years is to self-regenerate, healing as quickly as they are wounded, even replacing lost limbs.  I have found that fire or acid seems to be the only thing to negate this ability, which makes it very difficult to kill one if faced without that option. In my younger years as an adventurer, I have encountered them, and suffice to say, it is an event I do not want to repeat. But as a result, of those encounters, I have obtained a rather sufficient sample of the creature’s blood.
 
With this sample and its innate regenerative powers, I have been able to steadily increase the volume of it. Thus, providing ample opportunity for my apprentices to collect from it and bring it to you. Corked and sealed in a vial, to preserve its potency. Sufficient for all magical potions, magical studies, and spell components.