dafeeeeeeeeeesh
While Tyranus may think that the Inquisitor didn't see the rocks due to the lightspeeds, he is very much wrong. While the rocks might be going almost too fast to react, the psychic energy used to move them is not, and it is tugging from tyranus like if it was a tether pulling the rocks towards the Inquisitor.
The tips of the staff were still open, and as such, all it took was a swipe, and all the tethers were absorbed from the easily accessible psychic realm into the staff, charging it with the energy necessary to accelerate them to such speeds.
After that, the tip of the staff closes, and the dust seems to repel from the Inquisitor, as the rocks approach and..
They seemingly bounce off of an invisible barrier, but not a normal deflection, they bounce in a completely ellastic manner, the rock isn't even hurt, it is like it was shot from another angle, and they fly away with their speeds. However one of the rocks arrives too late, and strikes him clean in the lower torso. He doesn't seem to even bulge, the husk around the impact area is broken, but his body seems unscathed.
Dumb gearshift48
I'll give you something TRULLY unpredictable!
The tip of the staff opens up and shines an incredible bright light for some miliseconds, from which then comes multiple absurdly thin white lines of dense light, with enough energy to split the atoms of dust apart headed one towards the head of each one of the people surrounding him. The energetic beam would split atoms of the surface of whatever it hits, generating a small nuclear detonation.