Silver, by water balloons I mean the round blue projectiles that the 'toads' shoot at you (they don't really look like toads, they perch on houses and are black-ish) that bounce off of surfaces. I never really was a fan of using beast form because none of the foes' shots were auto-targeting, and since I was using a gamepad, spamming with energy form was always more expedient.
It's not that that Mithalas area was
hard per se, it was just annoying as hell. The way the houses are arranged, on a central stem that is sometimes solid and sometimes not (my dim LCD screen makes it a little harder to differentiate than it should be) was tricky, almost as bad as all those blasted mushrooms in the open waters earlier on. I tend to cruise along the walls while I'm swimming, and the houses kept encroaching closer and closer to the walls so I'd accidentally cling to it while jetting along. I never got into wall-boosting as a means of travel, so that was kind of obnoxious to me.
Hiro: using any area that is more cragulated as an arena basis will be more difficult than one with smooth walls, I would think. Anything like the large mushroom projections in the open waters, Mithalas houses, and Arnassi statues will delightfully complicate any combat situation.
For double the fun, don't give any visual cues (dimming of the item, foreground/background placement) to indicate which ones are solid and which aren't! You could do all
sorts of fun/cruel things by turning an arena into a veritable house of mirrors with solid and non-solid, foreground and background terrain objects.
Sudden death round? Random bubbles of air (like bubbles of water in the ice veil) to throw off speed and steering, even more than currents.

Oh, and don't forget to use loads of those mechanical crabs from the sun temple that shoot a crap-ton of purple tracer-shots at you, as well as the spiky plant dealies from the kelp forest that shoot three pink darts that follow you eternally. Having a cloud of tracer fire perpetually on your ass is good for getting the adrenaline going, regardless of whether your form is locked or not. If you're stuck in one form, no shield spell for you. If you can use the shield spell, that adds another element of strategy; "Do I want to hotkey into normal form, call up the shield, and try and bounce all these shots into my several hotly pursuing mutiluses, or do I stay in energy and hope to dodge while spitting out as much firepower as possible?"
<_<
>_>
Mua ha ha. >: D