Find some rotting bat wings in the basement of the LightHaven temple.
To do this, kill Undead Bats or carefully look on the ground.

Go to the Mage Tower in LightHaven.
Say work, then ingredient, and finally bat wings to Uranos.

If Uranos says he already has such wings, wait about ten minutes and try again.

Rewards:

• 2,500 XP
• Skull Dagger