Don't let it grab you, only tame during the days I you can out maneuver it. Fought one in South East lava cave and a level 12 killed me (lvl 97, 400 hp with 1762.2 armor rating) in less than 5 seconds after grabbing me.
Lured my 92 out of the chitin cave and had a friend grab and drop it onto our taming raft with metal, where we tamed him.
People say that is easy taming on day rather than night, but thats not truth because they always wake up, no matter how much torpor they have at 20:30 in game, that will cause you to lose all your taming process, I always tame these guys by starving them 2 times and then the 3rd knockout I put the food on its inventory, thanks for reading
Tame the mega during the day! It is extremly slower during the day due to wanting a rest. It is a very strong dino, it has been tested to be even stronger than the allo! Be careful if you tame it at night ;) caw