When channelers cast a spell, they need the energy _now_ and don't have the
luxury of deciding where it comes from. Energy is pulled from their own bodies
to fuel the incantation and later release of magical energy, which, over time,
can wear the caster out. By becoming more skilled with such spells they can
endure the strain of this energy reduction for a longer period of time before
giving out.
Flow of magic is available in the following guild: