Overlord

Incredibly simple, just harvest 10 lifeforce. This will be one of the first achievements you get in the game.

This achievement is very simple, and will be the first or 2nd achievement you obtain.

All you have to do is harvest 10 lifeforce. Lifeforce is the yellow orbs that enemies drop, after being killed. You can pick these orbs up by either walking next to them, or having your minions bring them to you.