if you are on fjordur and have a desmodus then you can go up and make it Hang on the cave's ceiling while shooting at magmasaurs

They will focus you, just go down and make sure to drag them into another place of the cave so the egg you wanna steal is free of any dangers

If there are onycs or any other npc near but you will wanna flee fast before the magmas catch you simply put the desmodus on passive and quickly pick the egg

NOTE: this can be done With any flyer that lets you hold weapons while riden (if you have the setting on)

I recommend desmodus because of his invisibility and abilty to be cave-friendly

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