If you are on rag just go in the ice cave then farm all the death worn horns in the world plus they are super easy to kill
How do you get horns on Valguero? I wanna tame a mantis
If your on rag I would recommend farming deathworm horns in the iceworm queen cave. The deathworms are super easy to kill and spawn way more frequently unlike the big ones that spawn in the desert.
Take a good baryonyx in a cryo to iceworm and deathworm horns are ez
A normal Deathworm drops 1 horn and the ice worm queen on rag drops 20.