Speak with Takar the Seer in the Barrens.
A succubus is a devourer of souls, destroyer of hearts, and dominator of minds. It knows nothing but evil.
This will be the creature you will learn to summon and control, but it cannot be brought into our world without a stimulus.
With a symbol of love as bait, it will surely answer your call. Then you can defeat it, and make it your tool.
It will be hard to find something of this nature, though. You should speak with Takar the Seer. You will find him in the Barrens of Kalimdor near Camp Taurajo.