Fog Combustion.
*BOOMMMM!!!*
That was the sound of someone making the mistake of attempting to strike the giants with a Cosmic phenomenon as it was swallowed up into the foggy giant's body and then shot back with twice the force.
*BAM!!!*
That was the sound of someone making the mistake of taking advantage of a giant's large frame and 'slow speed' to attempt a quick sidestep as he was caught by surprise when the giant moved with speed surpassing his own to slam the side of a purple spike into him and,
*CRACK!*
Was the sound that bore testament to the breaking of said individual's ribs.
Once this guy had been struck, people finally came to terms that while the purple spikes were physical and had mass, the fog itself was practically weightless, or more accurately, it was light enough to not be underestimated in terms of speed.