Center tip: as they have added the mosa to the center I've found the easiest way to knock one out is find one close to the bubbles get its Agro and swim in the bubble the mosa will get stuck and it can't hit you. Also this gives you unlimited oxygen and sanctuary from being attacked by anything else. ðŸ¤˜ðŸ¼
Besides the giga this is the hardest dinosaur to tame, note you will need a lot of narcotics and food. Before you begin the tame I recommend at least 2 to 3 full scuba suits for obvious reasons. You need to have at least a Ichthyosaurs or Megalodon, so you can actually move around and find a decent one. Once you find one you want to tame simply start shooting at it with the crossbow. Now right when you get his attention swim up, you should notice the Mosasaurs stops following you after a certain height. The Mosasurs cannot go higher than wherever it stopped. So simply park your water Dino above it and keep shooting it. If it runs off keep doing the same thing over and over again. Sooner or later you will take him down. Good job! Then simply use this app to figure out how many narcotics/food you will need to tame it. Once it is done enjoy your king of the water.
I've found that the easiest and fastest way to knock one out is to get its attention and swim through a gap in those large underwater stone formations,it will follow you and get stuck allowing you to shoot it as many times as needed
There is crystal cave on Ragnarok around 12,23ish where you can trap the mosa, I use a ichy to trap them as they are small enuf to get in the sallow area but the mosa can’t so they get stuck👍... hope this helps
Take an ichy. Get your best xbow (I prefer xbow because it’s easier to shoot and hit target on the back of the ichy) circle the mosa firing away. The ichy is quick enough to dodge the bite. If you dodge a wrench you can dodge a mosa.