The Warp Rifts sends the player to test out an experimental warp rift generator.
You will need:
Long have I wandered through Outland, searching for the truth of the void. Now I am old and weak. Perhaps you will help me?
I must learn the secrets of the voidwalkers. You must find the Warp Fields to the west. West of the Expedition Armory there is a dark place on the edge of the abyss where time and space are weak. Use my unstable warp rift generator in the Warp Fields to create a warp rift. You must gather warp nether from the creatures that come through.
When you arrive in the Warp Fields, you will need to right-click on the generator in your inventory. This will create a target on the ground. Click on the ground to generate a warp rift. Voidwalkers that emerge from this rift should drop the needed nethers.
Have you managed to use my experimental device yet? I think my unstable warp rift generator will work out there so close to the abyss.
Unbelievable. You have touched the void itself! <name>, you have saved my life's work. But there is more that must be done, and you can help me.