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.
Ragnarock - Go into ice cave and kill the weak deathworms there. Use a good shield to block their attacks and melee them with a sword, easy quick kills because they have so little health and they drop the same loot as a regular deathworm. Make sure to wear warm cloths.