Sam has the mutant ability to start an incendiary blast field around his body. It renders him almost completely invulnerable to all physical energy, as well as his passengers. By extending his blast field below him he can fly, though he lacks a lot of maneuverability. His speed is still increasing, almost that of the speed of sound. By extending his blast field forward, he can use it as an offensive kinetic blast, though the range is limited to about 10 feet.

Sam is also an External, a member of a race of extremely long lived mutants that are virtually immortal. He'll never age, recover from injuries quickly, and the only way to kill him is by removing his head.

With the death of his father, Sam became the head of a large Guthrie household at a very young age. He started working in the mine shafts and in a mine collapse, his mutant powers manifested. He eventually found his way to the X-Men through the nefarious plots of Donald Pierce and eventually joined the New Mutants. He eventually became co-leader with Dani Moonstar, and he became the only New Mutant to remain with the team through the team's lifetime.

After the New Mutants came under Cable's tutelage and became X-Force, tragedy struck and under attack from the fifth incarnation of the Brotherhood of Evil Mutants, Sam was apparently killed by Sauron. He rose from the dead and it was shown that he was an External just as Gideon is. Soon after this revelation Cable was lost to the X-Force during the X-Cutioner's Song, and Sam took over leadership. Cable returned, and Same stepped down but remained Deputy Field Leader.

X-Force has returned to the X-Mansion since losing their Murderworld base and Sam has been promoted to a full fledged X-Man. With this comes the drawback that his girlfriend, Tabitha, is still with X-Force, and there is still some tension.

Sam recently left the X-Men to return home and take care of his sick mother. He may be rejoining X-Force soon.