Even the most devoted of X-Men fans may think of Jean Grey as one of the most gifted psychics in Marvel's universe. And thanks to the Phoenix Force, once of the most dangerous, too. But many forget Jean's other mutant power, which she used to stand up to the Black Bolt of the Inhumans himself.
Admittedly, it's never been entirely clear just how powerful Jean Grey really is; part of the problem is that it's difficult to tell where Jean Grey ends and the Phoenix Force begins. Writer Jonathan Hickman has just relaunched the X-Men franchise, and he's attempted to clear things up by defining Jean Grey's powerset.
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Hickman has confirmed Jean is an Omega Level mutant, and that her telepathic and telekinetic power levels are very different. As he explained it in House of X #1:
"NOTE: Omega level is a classification of a single mutant power. While it is quite common that mutants manifest multiple powers, only one is normally of Omega level.
FOR EXAMPLE: While Jean Grey is both a telepath and a telekinetic, she is only an Omega level telepath."
This differentiation took longer-term readers by surprise, because frankly Jean Grey's telekinetic powers have long been portrayed as just as impressive as her telepathic abilities. This is perfectly illustrated by 1987's X-Factor annual, in which the X-Factor team were transported to the Inhuman city of Attilan and confronted the Inhumans. It turned out the villainous Maximus had used his mind-control powers to take control of his brother Black Bolt; he ordered Black Bolt to unleash a killing strike against Cyclops. Fortunately for Cyclops, Jean Grey intervened.
Black Bolt is generally considered one of the most powerful beings in the entire Marvel Universe, with enough power to crack a planet with just a whisper. On this occasion, he was lashing out unchecked, unable to restrain himself because of Maximus' influence. And yet Jean Grey - just Jean Grey, with no hint of the Phoenix Force - was able to hold it back. It's true that Jean found the experience exhausting, causing her to collapse - a scene equal to her regular fainting spells in X-Men: The Animated Series - but that doesn't make it any less impressive a feat.
Jonathan Hickman's X-Men relaunch has been well-received, but his account of Jean Grey's powerset is one of its most controversial elements. Hickman will be in charge of the X-Men franchise for quite some time, five years or more, but it's pretty certain a future writer will retcon this away. Hickman's definition of "Omega mutant" makes this rather more complicated, but no doubt some writer will be up for the challenge.