Squeezable Nuts
Eren got up from his initial position and headed straight to meet the berserker's charge who had been slowed down to a snail's speed from his perspective. The butcher ducked down and let the guy's fists pass from above his head.
Ron was a knuckle user. And he also had a wind-element spell in his repertoire. He would create quakes in the surroundings even with his fists landing on the thin air. That's how he had deflected the barrage of incoming attacks from Eren's teammates despite being surrounded.
And he was going to make the same fists to tackle Eren before the latter got a chance to execute his lightning-based spells on him. But he had underestimated the little terrorist in front of him.
All Ron could see was Eren seemingly vanishing into nothingness before appearing right under his torso. And the guy had already launched his attacks before he could change the position of his fists.
Eren grabbed Ron's almost-metal-like balls and executed Blitz Bolt once again.