Question is in the title

Kill with Drain Balls and bites

Drain balls indeed. It's when you press RT in flight mode*.

Sorry the drain balls got me.

How do you do the power bite?

Power bite is random like werewolf power attacks. The npc you are fighting must have low health, and then there is a chance you will power bite.

Power attacks? You mean send them flying? Or the kill animations that werewolf/humanoid can do? Its like a kill animation (just like the kind u do with weapons).

It does however seem to be a MUCH higher % of a powerbite happening then a normal finishing animation (Allmost everytime unless they die from something else, like the posion talons).

To perform the bite, the enemy needs to be at low health, enough to be killed by a power claw attack, hold down the attack trigger while standing still and facing your opponent. Most of the time this will execute the power attack bite, however other factors such as enemy position and elevation can cause you to perform a regular claw power attack. hope this helps

(please note, It doesn't seem to work if you are moving, so standing still is important)

(also if possible, get them to such low health that they are on the floor begging for mercy, I find it much easier this way)