[@GreivousKhan] [@Melonhead]

It largely depends on how thick the floor is. I do have doubt in the nether's ability to corrode stone so fast, as it seems to spread in form of flame. In that case, unless the floor has rather large cracks in it, it would take much more than a fraction of a second to penetrate far enough into the stone.

But nevermind all of the above: this move looks quite out-of-character to me in the first place. While Khan may know of Melon's penchant for kicks and knee strikes, Tordor has absolutely no reason to suspect Judgment of such a thing. All Tordor knows, is that one of his opponents is a large behemoth clad in armor and wielding a greatsword - and that isn't a premise from which you could reliably infer a jump attack. On the contrary, Tordor can only expect him to never let his feet leave the ground, using the sword as a weapon instead, as even kicks are seldom advocated in swordfighting, not to mention anything that involves jumping. Heck, Melon even mentioned himself that a horizontal slash to the torso was possible instead of the knee strike, meaning that the prediction is borderline metagaming.

The only way i can see Tordor moving the flame in time to get it underneath Judgments feet, where it would spend just a fraction of a second corroding the stone, is directing all of his attention away from Listia to catch the jump on pure reaction speed.