Oak was a Warpie - one of the children given superhuman powers by the reality-warping event known as the Jaspers Warp.
When Nigel Orpington-Smythe, then calling himself Peter, subverted the government agency R.C.X., he used the Warpies as his own private army. When he ordered the Warpies to bring in the superhero team Excalibur, Oak took part in the capture of Kylun. When Kylun was distracted by the fact that his mystical swords had no effect on Oak's teammate Ocelot (therefore meaning that the Warpies were not evil), Oak knocked him out with a punch. 
Later, when Excalibur attempted to escape from R.C.X.'s Cloud Nine facility, Oak was one of the many Warpies who fought them. Oak battled Captain Britain, whose powers were not fully functioning at the time. Oak pummelled the hero, but when Peter was encouraging Oak to deliver a killing blow, Oak rebelled against him, refusing to do so.
Powers and Abilities
Oak was skilled in hand-to-hand combat.