Firstly, it was me who put Arthur in he high tier, not Skalla, and that was before I fully understood the capabilities of other high tier characters and what was allowed, so it's debatable if be even actually does belong in the high tier. And even if he does, he's at he very bottom of it in terms of power, and what powers he does have are primarily melee focused. So in essence, you picked the single worst character you could have to fight Erde, a top-end high tier character whose powers have a two mile range. Arty has literally nothing that can be used accurately at that range (yet). So again, worst possible mat neuro you could have picked, since it starts out heaving slanted in favor of Erde simply by virtue of the characters used.
Secondly, your setup makes no sense. They start out two miles apart, and Erde is unaware of Arthur. Ok, good so far. Then we find out that Erde is surrounded by a ten foot thick stone wall in addition to his "body", even though he believes he's alone. Umm... Why? Why would be be wasting the effort? And then he just randomly decides that he's going to spikeify the ground for two miles in every direction, even though he still believes he's alone. Again, why?
I'm not sure you understand the concept of an advantage, as your entire scenario is as much in Erde's favor as it is possible to be, barring Erde knowing of Arthur's presence beforehand (an "advantage" you nullified with a completely non-sensical first attack).
Pick a character who actually belongs in high tier and try again.
