Getting these is pretty easy thank to the new Desmodus Draculae dino, just go in at night grab the egg turn invisible and fly out, or even eating organic polymer suicide with a fjorhawk on your shoulder (but the desmodus is a much safer option)
Magmasaur
The Magmasaur is a large creature that can swim in lava. Its saddle is fire resistant.

Player-written tips for taming, using, and fighting the Magmasaur in ARK: Survival Ascended & Evolved.
There is a new bug and you in which can enable smelting with a baby and older
my strategy on Fjordur is to have a rock drake lol. the stealth is very helpful for sneaking past the fire wyverns and cave creatures (x rock elementals too) and their dmg and hp can dispatch the magmas guarding the eggs
Don't use them to defeat Master Controller, they are strong, but they may burn you!
I use it to farm obsidian I when on one run on island map I was able to get 10k with a 200 atk a lot more than my ankys
Use a rock drake if you have one to turn invisible then steal
You Might want a Ferox or a Bloodstalker to get the eggs.
For taking one you can also use a enforcer if you have one from another world because you can use the teleport to evade the spit and grab the egg
I used a Procoptodon to get my first few eggs, put all the levels into movement speed and stam. It's dangerous and risky, but it works.
The best way is to go with two or more so one can distract and the other get the eggs.
For its full imprint you need ambergris so take Some of that its inside the volcano
Use a bloodstalker with a grappler hook get down before you grab the egg check if there’s no magmasaurs cause if you steal them in front of them all the near by ones will attack you after that run back up try not to be killed and ya
If u are on a cluster I would suggest getting a rockdrake then going to get a magmasaure because it makes it stupid easy to get them just go in invisible then hop off super quick grab the egg then dip
eggs are used to make extraordinary kibbles
The babies war ambergris, which can be mined from rocks with green glow on them in lunar biome.
You have to steal the egg and raise it yourself. You cant knock one out and tame it.
They need to be in lava to breed
FYI ambergris is NOT the only food for baby magmas, sulfur works as well.
If anyone are on fjorder use the andrewsarchus with a saddle and 10.000 health and when you get there pump in damage now and there you go a fierce egg ready to grow for you
If you can’t feed it then you can use the snow owl to heal it or you can use an admin command (giveinfinitestatstotarget)
On lost island you can run into the small magmasaur den and grab eggs easily