I made this Mote of Life farming guide to help out players who want to farm motes instead of buying them from the Auction House.
Primal Life comes from combining 10 Mote of Life, so if you need Primal Life, you have to farm Mote of Life.
Mote of Life
The Underbog is located inside The Coilfang Reservoir which is a giant machine in the middle of Serpent Lake in Zangarmarsh. Run to the center of that machine, then go underwater and swim through the pipe. The entrance to Underbog is the furthest right entrance after coming up from the water.
Clearing every trash mob before the first boss in The Underbog instance is the best way to farm Mote of Life. But make sure to switch the instance difficulty to Heroic, so you get more Mote of Life. (You can do this by right clicking over your own portrait)
Don't kill Hungarfen, or you can't reset the instance! (if you kill him by accident, you can switch back to normal mode)
One clear takes about 2-3 minutes, and you get 10-20 Mote of Life. After you killed the mobs, go outside and reset the Instance by right clicking over your own portrait then click the "Reset all instance" button. This restarts the whole instance and all mobs will be back. (You can only reset an instance 10 times in an hour.)
Farming giants around the Quagg Ridge in Zangarmarsh is a great alternative if you have a lower level character.