Be careful with traps in Lava biome, if a Magmasaur Argos to your structure, it can blast a huge hole in your stone easily. One got trapped in our pitfall trap and we became aware of it from the tribe log showing it had destroyed half the building in minutes. This was NOT a small structure either. Best to break it out and kite it away (or eat it with Rexes). Stone, metal and Tek are all damaged or destroyed by this thing. It was not designed to be trapped or to be held in structures. If you want to tame one, steal an egg.
If you get too close to a wild one that used it's special ability (a charge that will set it on fire and aggravate nearby dinos) it'll display a message saying "getting hot! Stay away!!!!" and that will set you on fire. Don't approach unless you know you're prepared.
The magmasaur has a very very bad turning radius when trying to kill one try to continuously try to be behind it. It’s flaming aura when using its spit will hurt you, the magmasaurs body will become in fire whilst doing this attack that will be your warning. Magmasaurs also come in packs of 1-3 so if you hit one another one will most likely be there
They can be found almost everywhere in the volcano biome however the nests that contain the eggs are located inside the volcano. Easiest entrance inside is next to the "Egg-straction" mission beacon. The nests are located in pools of lava a nest can hold anywhere from 1 to 3 eggs. The lava pools tend to have minimum 1 dozen adult magmasaura that will start hurling fireballs in your direction once you take a single egg. They are quiet slow moving a ferox will be useful in getting in and escaping. The pools of lava aren't an instant kill.
Stay still because they are the first creacher to have the sense of when you are not moving thay can’t see you and if you hit them thet deal damige back to you so if you one hit them they will deal a persentage of damage to you and your mount