My Terrae Magus is about to summon/rarify his first Earth Elemental, with a Might of 20.
Since he is a Terrae Magus, and has a decent score in Lore: Terrae Magus Cult and Magic Lore, the gamemaster allows me to custom the elemental my character is going to summon.
I would like Elementals with the ability to merge with ground (be is earth or stone), and travel through it (the basic idea is that i have this scene in my mind where Elementals rise from the ground on their master's command, ready to obey him). Eventually, they should be able to perceive their surrounding from under the ground.
How would you design such an effect with Magic Qualities system? How about a magus able to achieve same ability with spells?
Earth is the ultimate static, non-moving material; I don't think this would be a very common power. Rather, earth elementals would flatten themselves out to be one corpuscle thick (like someone had scattered a layer of dice onto the surface; or indeed, take up the form of a mosaic) and then flow over the surface. Certainly I wouldn't have them move through rock, but I guess you could have them move through soil like a burrowing animal.
An effect of this type is best conceived as a Personal Power, using ReTe to move the soil out of the way.
Swimming the Currents of the Earth, 0 points, Init Qik -2, Terram: the elemental can swim through soil or sand by moving it around its body. As long as the soil contains only small rocks these will be moved aside with the soil, but larger boulders (relative to the size of the elemental) are a barrier to movement. If the soil is not as deep as the elemental is tall, then its movement is apparent to those on the surface. If the soil is half the depth of the elemental's height it cannot use this power at all. ReTe 15 (Base 2, +1 Touch, +2 Sun, +1 Part, +1 intricacy) Personal Power (15 levels, -2 Might cost).
This moves 10 cubic paces of dirt; elementals larger than Size 0 will need Size modifiers. The level 2 guideline is enough to turn packed earth to plowed soil, but the need to move the soil around the creature needs an intricacy modifier in my opinion. This effect can be a ReTe 15 spell for a magus.
To see while under the ground, use a variant of Prying Eyes that uses T: Part. This allows the elemental to perceive anything touching the Part of the soil that it is touching.