Holding the creepy pac-disc would provide some clarity!

As to the location of the others, it would unfortunately be more spread out. The pool is at the center of the space, and most intermediaries further toward the back. The rest of the combatants, however, are anywhere and everywhere around. Lavellan would be perfectly capable of blocking the pool with a cave-in, but unless he was able to direct where the rocks fell, there would be some risk of hitting others.