In Entry #2 for Hunters of Dune, I brought up that the Oracle and the old couple have this power to spread themselves over vast spaces and that they are keys to the ending of this story. The following scene is very important and couldn't be easily clipped so I am sharing a large portion of it here.
The Oracle. Her mind was unimaginably advanced, beyond any level even a Navigator's prescience could attain. The Oracle was the ancient foundation of the Guild, a comforting anchor for all Navigators.
"This altered universe is where I last saw the no-ship piloted by Duncan Idaho. I helped his ship break free, returning him to normal space. But I have lost them again. Because the hunters continue to search for them with their tachyon net, we must find the ship first. Kralizec is indeed upon us, and the ultimate Kwisatz Haderach is aboard that no-ship. Both sides in the Great War want him for their victory."
The echoes of her thoughts filled Edrik's soul with a cold terror that threatened to unwind him. He had heard legends of Kralizec, the battle at the end of the universe, and had dismissed them as no more than human superstitions. But if the Oracle was concerned about it ...
Who was Duncan Idaho? What no-ship was she speaking of? And, most amazing of all, how could even the Oracle be blinded to it? Always in the past, her voice had been a reassuring and guiding force. Now Edrik sensed uncertainty in her mind.
"I have searched, but I cannot find it. It is a tangle through all the prescient lines I can envision. My Navigators, I must make you aware. I may be forced to call upon you for assistance, if this threat is what I think it is."
Edrik's mind reeled. He felt dismay of the Navigators around him. Some of them unable to process this new information that shook their fragile holds on reality, spun into madness within their tanks of spice gas.
"The threat, Oracle," Edrik said, "is that we have no melange--"
"The threat is Kralizec." Her voice boomed through every Navigator's mind. "I will summon you, when I require my Navigators."
With a lurch, she hurled all of the thousands of great Heighliners back out of the strange universe, scattering them into normal space. Edrik reeled, trying to orient himself and his ship.
The Navigators were all confused and agitated.
Despite the Oracle's call, Edrik clung to a far more selfish concern: How can we help the Oracle, if we are all starved for spice?
(Hunters of Dune, pp. 175 - 176)