Rego spells can build things and perform the work of a craftsman in an instant. I’m certain they could deconstruct a complex thing as well as build one. Or wreck something in a manner consistent to the skills of a craftsman. Why? Well materials are expensive and also not always abundant. Deconstruct a castle into reusable materials and then build a new one elsewhere.
Starting with a spell which performs the work of a laborer for one day, we have to decide how hard it is to knock out bricks. Let’s say it’s an Easy task, which requires a base Finesse difficulty check of 6+. Then we see check that a Rego Terram effect can manipulate a cubic pace of material, which sounds reasonable for a day’s work.
In the spell design it’s plausible to increase the amount of work performed, or increase the materials affected; however that raises both the Finesse difficulty and the effect level. It is better to create a lower level simple effect and use an item to allow it to be used repeatedly.
Deconstruct the Obtrusive Wall
Rego Terram 10, R: Touch, D: Momentary, T: Part
This spell removes, cleans, and stacks Terram based materials from a targeted structure. The spell makes no account for the structural integrity of the affected surface, but will remove the bricks safely and stacks them neatly to the side. A finesse check of 6+ is required to perform the spell neatly and quickly.
(Base 3, +1 Touch, +1 Part, +1 stone)
Then modified in an item as: +10 unlimited uses; for a final device level 20.
These effects, like all the others I’ve pondered are part of a new spells compendium for Ars Magica.