Activate Marrow-Gnawer by tapping it and sacrificing another Rat, creating at least one 1/1 Rat creature token.
When the Rat enters the battlefield as a Pirate due to Xenograft, Coercive Recruiter triggers, untapping Marrow-Gnawer.
Repeat.
If you control at least two other Rats, this combo creates infinite additional Coercive Recruiter triggers, which can be used to untap any creature(s) infinitely and/or to gain control of any number of creature(s) until end of turn.
Results
Gain control of any number of creatures until end of turn.