Nothing has been revealed about Phinn Mac Mram, what is know is that he is not a native of our Earth. Phinn Mac Mram came from a world in which biological life did not evolved into it lead to the birth of the Mechclans after some undisclosed amount of time biological life start to spring forward, this was the mysterious Cyber-Sidhe. Phinn quickly rose up as the leader of the Cyber-Sidhe and use his power to enslaved the Mechclans and demands sacrifices from them however this dream of conquering his native Earth came to a stop when the Mechclans came together and vanish him to another world through a Henge-Nodes a sort of dimension portals that exist in their world.
Stranger on a Strange Land
Upon arriving in Earth-616 Phinn was confuse but he did not allow this to get in the way of his dreams. He and his band of Cyber-Sidhe begun to wrack havoc on the world. The newly capture and member of A.R.M.O.R. Lyra herself a non-native of our reality was send to battle Phinn to prove her worth. Phinn believe that the resident of this world were ask weak as the Mechclan however that was far from truth and Lyra easily demonstrated the capability of destroying his army. Knowing this Phinn intervene and challenge her to a single combat, fearing that she may refuse Phinn took several human hostages. Unknown to Phinn, Lyra was supreme warrior of her people and she easily beat him ripping his robotic heart and freeing his artificial soul, the remaining Cyber-Sidhe chose to surrender.
As a Cyber-Sidhe Phinn is a "natural cyborg" meaning he was born with mechanical parts that were already attached to his biological body this gives him increase strength, stamina and reflexes. He also wielded a Vibranium spear which he use with incredible skill. Lastly as with all Cyber-Sidhe he seemed to be able to infect machines with the Chromedruids a sort of programing code know as the Ogham Code that is able to overwrite them into his loyalty. How the Chromedruis works still unknown.