Dive Bombs... can someone explain?

[Aphel]

We stack at the bottom of the slope to, like Able said, cheese the mechanics. Imagine her Divebomb as Titan's Landslide, except targeted.

Her Divebomb effect is like a ruler(that tool you use to measure length with) or a ribbon: Flat and long. Keep the ruler placed flat on the ground and poke things with it. That's her Divebomb (LOL). This works well if the arena is completely flat. However once height is thrown into the equation it doesn't work so well.

Now imagine you guys are down in the bottom of that ditch and Twintania (at the side of the arena, on a higher elevation) starts a Divebomb. That 'ruler' is essentially 'buried' into the ground in order to make a straight line from the source to the target. So the only point of exposure to her AOE is at that tiny spot at the bottom of the ditch. You've essentially taken advantage of the fact that her AOE is flat.

Until SE tweaks the way AOEs work, this is why most, if not all, boss arenas are designed to be flat.