Manticore Is one of the major players in the Freedom Phalanx, as well as being the alter-ego of dev Sean Michael Fish. He seems to be a bit of a cross between Green Arrow and Batman.
Justin Sinclair is currently following the tradition his father started. When his father, the first Manticore, and mother were slain in front of him by the villain Protean he was raised by Michael White, the Back Alley Brawler. Eventually, he tracked down and apparently killed Protean. He's by far the 'darkest' of the Freedom Phalanx, in addition to being its only non-powered member. He's even founded the Wyvern, a mercenary hero group to do what the more law-abiding Longbow will not, without the knowledge of the rest of the Phalanx. This attitude puts him at odds with Statesman, Statesman believes Manticore is too reckless while Manticore believes Statesman has given into his own hype, although at the end of the day they're still teammates.
Manticore's fighting ability comes from his variety of extremely expensive trick arrows, paid for with his family fortune. He's also able to tap into Paragon City's Mediport system to teleport around. In one issue of the comic he gained the ability to teleport his arrows through things, however this hasn't shown up anywhere else so it's safe to assume it was either temporary or non-canon.
Manticore watches over Crey in Brickstown, and offers a task force to heroes level 30-35, in which you hunt the Countess and her bodyguard. It's a fairly decent Task Force and offers a good opportunity to work towards a 'Conspiracy Theorist' Accolade badge.