Pulmonoscorpius Kibble (MOBILE) is used to tame the Rex, and the Beelzebufo.To make Pulmonoscorpius Kibble (MOBILE), combine Pulmonoscorpius Egg, Longrass, Prime Meat Jerky, Mejoberry, Fiber, and Waterskin in a Cooking Pot. Start the fire and cook for 30 seconds. It spoils in 3 days.
Honestly if you don't wanna go back and forth to caves to get scorpion eggs, a easier and less dangerous method is to find a female scorpion, and tame it. It's really no problem just knock em out while not getting to close and feed then rotting meat. Now you won't have to go back and forth. And they really are great tames, good for knocking things out.