While playing survival, you get yourself a megatherium, head on over to the dunes, start killing yourself some bugs, use the orbital camera to search out a deathworm. It levels you and your mount SUPER fast. Then you can literally hunt down deathworms. By the way, a high level megatherium can kill a rock golem.... hint hint.
Use Sword and a mastercraft shield. Block worm's attack, then attack it twice and put your shield up quickly for worm's next attack. Rinse lather repeat. If you get knocked back too far the sword won't hit. Maintain push towards the worm to stay close while shielding. Practice the timing. When looking for them. Go on foot. They will find you. When u see a dust circle on ground in front, put your shield up for worm's surprise attack and jus keep up the pattern I mentioned. You can it twice after every block. That's how its done on foot.