Why doesn't Vaarsuvius use a wizard's staff?

[Kish]

Couldn't Malack just use Gaseous Form and go right through? At least in the comic it's always been presented as an actual cage with bars, not a solid energy barrier.

Either bars of force or solid walls of force, caster's choice.

The smaller solid walls version would have been too small to contain the ancient black dragon at all; Malack is slightly smaller than her.

I am, however, blinking at the idea that level 7 is "relatively low-level."