Ordinary Mode:

At a glance: A fairly ordinary looking man in his mid twenties, his clothes are worn and his aged armor looks like it was stolen from a crypt. He carries with him an ornate Greatsword, but the blade is shattered rendering the item relatively useless.

If you continue to stare: You may notice that there is something very wrong with this man, his eyes are dull and hollow, his complexion is pale and drawn out from lack of sleep or grief. You may sense a violent and chaotic aura that lingers just beneath the surface.

The Other Mode:

The creature before you is an abomination. An impossible  beast of darkness and chaos that shouldnt exist in the material world. It floats about sadistically, flaunting natural laws. At its side floats what looks like a sword, the blade ripples and moves like a thousand black snakes scrambling to escape some gap or rift in the fabric of reality. The creature seems to physically reject light, a dark black shadow follows him wherever he appears.

Once the creature is gone from site, your mind may choose to reject any memory of the encounter rather than come to terms with what it has seen.