Curse of Lycanthropy (Rat)

You have contracted lycanthropy from a bite wound given by one of the cursed. A character who becomes a lycanthrope retains his or her statistics except as specified by lycanthrope type. The character gains the lycanthrope’s speeds in nonhumanoid form, damage immunities, traits, and actions that don’t involve equipment. The character can’t speak while in animal form. A non-lycanthrope humanoid hit by an attack that carries the curse of lycanthropy must succeed on a Constitution saving throw (DC 8 + the lycanthrope’s proficiency bonus + the lycanthrope’s Constitution modifier) or be cursed. If the character embraces the curse, his or her alignment becomes the one defined for the lycanthrope. A character with this Curse is under DM control until the curse of lycanthropy is removed.

Rat: Wererats are cunning lycanthropes with sly, avaricious personalities. They are wiry and twitchy in humanoid form, with thin hair and darting eyes. In their humanoid and hybrid forms, wererats prefer light weapons and use ambush tactics rather than fighting as a pack. Although a wererat can deliver a nasty bite in its rat form, it favors that form for stealthy infiltration and escape rather than combat.

• Your animal form is a giant rat, which is small. Your statistics, other than your size, are the same in this form. Any equipment you're wearing or carrying isn’t transformed. 
• You gain a Dexterity of 15 if your score isn't already higher.
• While transformed you gain a bite attack.
• You gain Darkvision up to 60ft.
• You gain advantage on Wisdom (Perception) checks that rely on smell.