Jassad's Bestiary is a in Might & Magic X: Legacy. You get this quest by talking to Jassad in the Goblin Watchtower, the Inn of Sorpigal by the Sea. Register 10 creatures in the Bestiary. After you find the first 10 entries, go back and report it. Afterwards, you can continue to find more; you receive an onscreen message when you have fulfilled the quest objective and the quest will update. Now, you need to find even more creatures; you should return to Jassad each time you receive the onscreen message to get your reward.