Mangog is the living embodiment of an entire race of people. Billions and billions of people. Mangog's race was a conquering people. After wiping out thousands of galaxies they tried to invade Asgard. Odin banished all of them, but before dying they found a way to channel all their rage and power into one being- to exact their revenge. Even after Odin restored Mangog's people to life the embodiment of Mangog could not be erased as his evil was too powerful.
Mangog feeds off strong emotions (particularly negative) such as hatred, anger and extreme devotion. He possesses god-like strength and durability. He is able to knock out Asgardians and even Thor with a single powerful punch. His durability allows him to withstand attacks from that of Odin. He has superhuman recuperative abilities and if an attack is capable of putting him down temporarily, Mangog will recover in a matter of seconds. Mangog also has the ability to manipulate vast magical energies for various effects, including projection of concussive force, molecular manipulation of others.
Mangog wages war on Asgard and all who stand in his way in an attempt to get to the Odinsword.Vengeance for Odin destroying his entire race.A race Odin eventually brings back to life,after defeating the Mangog.Except for Odin,no one really does much that's effective against him here.
Thor 250: (Mangog was empowered by the Asgardian's beliefs here.) By text on first page, one can see Mangog doesn't view himself as Odin's equal. Mangog has been using the guise of Odin for several issues prior.