If you can transfer your Rock Drake to Genesis it is pretty easy to steal Magmasaur eggs with them. Just turn invisible look for the best egg to steal. Quickly dismount grab the egg get back on and haul your butt out of there.
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.
Easiest thing to do is to spawn at the East zone and go to the Egg-Straction mission. Then, take the first left in the cave and you should end up by the nest. A good strategy is to wait until there aren’t any magmasaurs by an egg, then ask HLNA to teleport away, and right before you teleport, grab the egg.
Get something fast to go in The Volcano, and wait till right after it erupts. This ensures that you won't be charred to pieces by the mountain. If you don't know where to go, use the mission "Eggtraction" in the gamma form. If you do, great. Once you're in the pool, catch 2-3 eggs for breeding.
The three attacks are taunt, Searing Spit and bite. Taunt is best for hunting for your carnivores. Easy way to hunt. Searing Spit costs metal ingots, which you can smelt inside the magma, and does a lot of damage in pvp and pve missions that aren't other magmas. Bite is, well, bite. Your magma can also collect wood, thatch, metal, rock and flint very well. Can only be bred in lava.
If you encounter in a magma saddle, you should be good. If you aren't on a magma, make sure to whistle some very very strong tames. These things will burn you to death. Get close, you get