Tavern Rats (Spellmonkeys) by Matt Youngmark

All Frinzil ever wanted was to study magic, but with three years of back tuition due, she’s about to be kicked out of school forever. When she stumbles upon the location of a legendary scroll, she thinks her money troubles are over... until the adventurers she hires to retrieve it immediately tromp off to snatch the treasure for themselves.
Now her ragtag band of spellmonkeys (a bumbling orcish summoner, a fog-headed druid, and a demon-worshipping nightmare—basically, the dregs of the adventurer’s tavern that no other party would take) will have to face the perils of Gluumwilde forest and find the Temple of Unrelenting Evil before the professionals get there first.
Assuming, of course, that they can even survive the trip.