We don't know for certain that she's a warlock, Jessie," said Will.
Jessamine ignored him. "Is it dreadful, being so evil? Are you worried you'll go to hell?" She leaned closer to Tessa. "What do you think the Devil's like?"
Tessa set her fork down. "Would you like to meet him? I could summon him up in a trice if you like. Being a warlock, and all.

Author: Cassandra Clare