Actually, if he has instinctual, localized control, of mass/density, he can mimic nigh invulnerability, flight, super speed, strength and endurance.
Starting in order:
He can make himself extra dense while making everything in his proximity less dense: this would lessen the amount of energy he is hit with and better allow him to absorb it without being knocked around
The most complex use of the power, the simplest way to fly is to make himself lighter than air, but this lacks a stable means of lateral movement in and off itself. An alternative to the above is he could make the air above himself less dense while also making the air around and beneath himself heavier: lighter than air is a relative concept, and if the air above him is lighter its less able to weigh him down ;3
and as for getting around he would have several options starting with Swimming through the air! (with extra thick air to push himself off of he could actually swim around rather than hover around comically while trying to swim in normal thin air.) Something he could also do in additon to or in place of would be to make half of the air infront of himself, the upper half, lighter then the surrounding air while making the lower half heavier, causing it to vacate the area in front of him and make a constant vacuum that vacuums him along, he could do the inverse behind himself for an added bit of thrust.
Oddly enough, with this means of thrust he would go fastest standing strait up rather than in a ‘superman’ pose or the like.
and as for speed: make any body part going forwards exceptionally light, and any part being used to push the rest of the body heavy, using the trick above to push air out of the way and onto to the character’s back can add even more speed.
Oddly enough he would be at his strongest when he is at his lightest: as normal you’re lifting both yourself and the object your lifting, but yourself is simply a given that is ignored ;3 making this lighter also helps mimicking raw strength, but he would be unable to do any hulk smash stuff (without smashing his own bones, Denser dos not mean tougher, glass is dense.
an odd aspect of using this power for ‘super strength’ is he can make himself and the object he is lifting, with the exception of his feet that would instead be super dense, very light and basically ignore his and the object’s combined center of gravity, allowing him to, possibly, uproot a tree and then use it as a baseball bat: with only super human strength, no matter how strong, swinging a tree like a bat would be imposable.
And making his body generally lighter means its working less hard, and thus able to do so for longer :3
Just a few thoughts
