Boreas is an Olympian god and presumably has the typical powers and abilities of one, though to what degree he has these is not yet clear. He presumably has superhuman strength, speed, durability, healing, reflexes and immortality. In addition to these he has demonstrated winged flight and super-cold breath.
In the wake of the Chaos War a new mountain was created by Zeus, All-father of the Greco-Roman/Olympian gods, to be the Olympians' new home. Having just aided Hercules against the Chaos King and therby helping to save the entire multiverse, Bruce Banner (the Hulk) sought a remedy for himself and all the other Hulks' curse(s) of being Hulks from Hercules who'd wielded power on a near-omnipotent scale to defeat the Chaos King and repair the multiverse. When Hercules informed Banner that he'd used all of his power in those efforts and therefore couldn't help him, Banner decided to scale the mountain and petition Zeus for help instead. Banner then had Hercules help him to become the Hulk. While scaling the mountain, the Hulk was attacked by many gods, goddesses and other Olympian beings who tried to prevent him from reaching the top. Boreas was one of these Olympians. He attacked the Hulk with a withering blast of super-cold breath which the Hulk withstood and overcame to continue his quest to the top of the mountain.