From the Abyss

My warp rift generator is complete. You can now use it to summon a true prince of the void, a creature whose soul shard will tell us much of what lies beyond.

Go south in Void Ridge and use my warp rift generator near the void stones. Look for a cluster of crystals near the edge of the abyss. A huge warp rift will form and Void Baron Galaxis will surely appear.

Destroy this creature and bring me his soul shard.