Pol Sanderson had always been slow moving. That was why he was the last out when Kaon's experiment failed. It changed him into something that absorbed matter as it moved and added it to its form to become Super Massive.
(I guess the mechanic would be ka built into a damage shield, absorption of body from object to feed density increase and strength. Not sure. The effect is when the power cuts on, it sucks in anything he is touching and builds a super tough form around him until he cuts it off. At the top end, I believe that he would stop moving and just absorb anything until something was done to shut him down.)