I’ve found the eggs. The eggs are located inside the volcano in an amethyst cave. There are lava pools with groups of magmasaurs in them. There are small islands with craters in them, within those craters the eggs are nestled within. But be careful there are lots of magmasaurs, magma, and what look like varient rock elementals.
On fjordur is you go into the cave at the end of the fire wyvern trench and fly to the nests steal one egg then lead the rest of the magmas under the bridge in that area lead them against the right wall going in with the spikes when there all in there enjoy getting all the other eggs in that area I got lots of eggs doing this