Snoke's power.
Let's talk about this guy and what how strong he might be.
He is Kylo Rens master so anything Kylo knows Snoke knows so That's a given.
He dominated Rey, though new sources reveal that despite her raw power she still is inexperienced with it.
We know that Snoke knows the knowledge that Palpatine wanted to know in the Unknown Regions. With this knowledge, he was able to help the First Order survive against the "Dark things" that inhabit the UR. The UR in Disney Canon is where Force religions like the Jedi and Sith come from and knowledge has been lost since then. He is also said to be strong in the Force and a master of the dark side.
However, despite being a powerful master of the dark side and strong in the Force, his body is so broken and painful that unlike Palpatine he needs his Praetorian Guards to help him in case of violent confrontation. We caught a glimpse of that IMO when Kylo tried to fight and got struck by lightning with his Guards coming in to protect him a moment later.
We also know in his youth he was a strong warrior and he defeated legions of enemies and also that he far stronger than Vader and Palpatine thanks to his "Endless Resources" both things were said by Andy Serkis, Snokes actor. The endless resources thing can be intetpreted in a number of ways.
That's all we know on Snokes power at the moment. Palpatine apparently sensed something so powerful in the UR he actually believed it was the heart of the dark side. Originally people thought that might have been Snoke but thanks to the new novel plus how he died that might be no longer the case. The new novel being "Thrawn: Alliances" this might be connected to the dark things mentioned in the UR. We might see books talking about this post episode 9. In the novel there was this weird.species kidnapping force sensitive Chiss to try and make an army of force users. Not connected to Snoke but in case you were interested.