To acquire the eggs of a magmasaur you have to actually go into the volcano in the volcanic region. The entrance of the cave is very noticeable with bright glowing purple crystals around it. Going inside you’ll find smaller creatures (onycs, araneos, and pulmonoscorpiuses) and larger much more threatening creatures like magmasaurs and rock golems. When in the cave watch out for araneos since getting webbed by them is practically a death sentence and be careful of magmasaurs shooting their searing spit (fireball) at you since it has a very long range. After grabbing the egg I recommend grappling to the ceiling and using a parachute down but also spam grappling to get away from magmasaurs work. Be extremely careful when getting these eggs and make sure you’re prepared to take care of the baby when raising because it is a major chore and you don’t want to waste effort.
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.
1. Find an egg with no magmasaurs within regular aggro range. Stand next to it and teleport away via HLNA. Whenever the haxagon walls of the bubble are about to reach the top, take the egg and you will be safely teleport out.
2. Get a Bloodstalker. Jump up high and slowly drift down using control (PC)/LB + RB (Xbox)/ L1 + R1 (PS) until you can see an egg, any egg. Once you’ve found one, release the drifting button(s) and get off of the Bloodstalker, take the egg, get back on the Bloodstalker and grapple to a high up point, you will be out of range of the magmasaurs and you can then safely escape.
To hatch the egg you will need 20 standing torches for it to hatch in any weather (not sure about Arctic zones). You will need to feed the baby Ambergris which can be acquired through mining the rocks with green glowing veins in them in the Lunar biome with a pickaxe or mining drill or anky. The Bloodstalker is very useful for traversing the Lunar biome. You can also get mastercraft Magmasaur saddles at a decent rate from the Bottle Nosed Blitz mission, which is very easy, even on alpha. Hope this helps
Easiest way to steal an egg is teleport East volcanic, locate the mission The Egg-Straction and enter the cave. Note parachutes can be used but wing suit is better. Once you are in the cave use parachutes or a wing suit to fly into one of the little ravines and land by an egg that there are no nearby magmasaurs. Then start a teleport and as you are about to teleport pick up the egg.