Managarmr keeps dying

its not random lag, i tamed a 270 mana with a 12k hp base, right after it got f*cked by a random 120 mana and it was on NEUTRAL is this a glitch or do manas die this easy, this is my first time taming one

edit: Tamed a 280 and it got killed by a 30 sabertooth... f*cking help me please