As soon as the fight starts save, that way if you die you can just reload the save and try again. When the fight starts you must shoot natla until her half is about halfway down. When she's about halfway down she will have a rage meter. You must shoot her until the rage meter is full then when she rushes at you do a forward dodge that does a flip towards her (the point of this is instead of hitting her in the head like normal with an adrenaline attack you have to hit the green spot on her back). Hitting her in the back with an adrenaline attack will stun her, when she's stunned shoot her as much as you can. Rinse and repeat and when her health's gone a super action will start, complete the super action to defeat her.