Where do you find doom gaze in final fantasy 6?

If you mean death gaze, you're going to need an airship for that. It's a slow and painful process, but it's somewhat simple. The simplest way is to land the airship, board, and turn a couple degrees right or left (just a tap, not 30 degrees). This way, you'll be slowly climbing the map, but hitting ever space in the air. Eventually, you'll run into him. Damage, he'll run, but retain the damage. Track him down again, and repeat until he's dead.