A shapeshifter who can assume the shape of a rat.(noun)
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Use "wererat" in a sentence
"Wanted: 1 artistically-inclined male bi/gay wererat."
"Like an apparition, there stood in the midst of the melee a giant saber-toothed tiger, its jaws dripping blood from the wererat it had just bitten in half."
"This assumes your DM allows you to remain a PC, mind you, and you might not like to change your alignment (but that still leaves wererat as a lycanthrope option)."