The Rabbit and the Mushroom

When Adrian the Brave, an arrogant con-artist posing as a knight, eats a mushroom he finds deep in the forest by his village, his life takes a turn for the worst.
Immediately after he eats it, he becomes addicted. In his search for more mushrooms, he finds a trapped rabbit. The rabbit, whom he nicknames "Lackwit," offers to lead Adrian to an enchanted part of the forest where the magical mushrooms thrive, in exchange for freedom.
Adrian soon discovers, however, that this forest is home to more than just mushrooms, and not all of the inhabitants are what they appear to be....

Cover illustration by Anthony Moravian. http://antmora.deviantart.com