Barracoon the Piper is the Champion of the Vermin Horde Spawn.
Although Barracoon appears to be a normal human, he should not be underestimated, because he has some very interesting abilities and a very large amount of hit points.
When Barracoon is damaged by a player or pet, there is a large chance that the attacker will be polymorhed into the shape of a Ratman. If in Felucca, this will result in the target turining grey and as such become freely attackable by anyone. (Polymorphed pets do not turn grey)
The polymorphing can be prevented by wearing Savage Kin Paint or by casting polymorph yourself before Barracoon gets the chance (polymorphing into anything but a human male or female shape will also turn you grey).
Barracoon can also play a small tune that will summon a small group of Ratmen, Ratman Archers and Ratman Mages. The Ratmen will immediately attack whoever they were summoned upon.
The last of his abilities is that he can polymorph himself into a ratman, that combined with his summoning ability can make him very difficult to locate.
The polymorph spell will last a few minutes both on Pets, Playesr and Barracoon himself.
When Barracoon is killed in Felucca, a Scroll of Power will be placed in the backpack of some of the players who damaged him. Additionally one of those who damaged him will also get a "Skull of Greed", which is one of the six skulls needed to summon the Harrower.
The clothes Barracoon is wearing can also be found on his body when he dies.
Picture courtesy of http://www5a.biglobe.ne.jp/~parari/uo/