You only get one pet, the abomination. This pet gets upgrade as you level though, with the highest upgrade coming at level 50 (Awaken Abomination III).
You get a spell at level 10 called Necropsy that allows you to harvest parts from corpses, with a chance of getting something called a graft - addon for your pet that can give bonuses to the abomination or special attacks (which you can control).
There are also several temporary "pet" spells that reanimate corpses to fight for you for a short time only.
Currently the class has a few mishaps (ie pet damage is a bit low at higher levels). However, I enjoy my necromancer and am contemplating playing one at launch.
Feel free to check out our
Necromancer Section here in our
WikiSphere.