Call for Judgment: Thievery

As stated in the first paragraph of Rule 13: Spells:

Sorcerors can cast the following spells, each of which costs some amount of Power, and depletes some combination of Water, Earth, Air, and Fire reserves when the spell is cast. A sorceror must have the required amounts of Power and Magical Energy at the time of casting (this is to prevent spells like "gives a Sorceror 3 Fire. Costs 2 Fire.") Proposing a new spell to be added to the spell list is always a trivial proposal.

As such, I believe that Proposal: Stop Thief! has always been trivial, and that Mat should be docked 8 Power in accordance with the nontrivial / trivial award system.