One Ugly Mother Achievement
One Ugly Mother30
Complete Predator Campaign on Nightmare difficulty settingGeneral Information for Nightmare as Predator
To be frank, the first two missions are horrible. You don't have Alien Vision, no disc and no Spear and fighting Aliens in close combat can be difficult. Once you get your gear back it will be easier. To fight them in a effective way try to use the jump attack to weaken them. After a successful block you can land two light attacks.
Preying Marines makes less fun than as Alien, since you are not so quick. To make your life easier look for a good place to retreat to and make use of the plasma caster or lay proximity mines and distract marines to them.
Don't forget to activate stealth with as it doesn't cost energy. If you are unsure wait awaits you in the mission, replay it on Hard and try to remember as much as possible. Good luck huntin'.
How to beat the Predalien:
Check at 3:40+ min how to kill it quite fast without much effort.