Wielding the Rock of Extended-Range
ReTe 5, R: Touch; D: Mom; T: Ind
You touch a rock and it is propelled into the air at speed, in a direction you dictate, striking anything in its path.
(Base 4, +1 Touch)
Is this spell valid? The range of touch is the range to the target, which is the rock which you are controlling, but the range to anything the rock hits is voice (potentially even sight). Note that this spell is a Touch variant of "Wielding the Invisible Sling", ArsM5, p. 155. On a similar note, why does Wielding the Inv. Sling say that it hurls the object "at any target within range"? If the stone I want to throw is in voice range, surely that satisfies the demands of range to target, and the secondary target (of the stone throw itself) could be outside voice range.
We could say that range dictates not only range to target of original effect, but range into which that effect can extend. But then that means that if I cast a Touch MuCo spell to give someone rabbit ears for a month and then walk away, the rabbit ears should disappear, as the rabbit ears effect cannot occur outside of Touch range from me.
We could say that if I cast Invisible Sling I am controlling the object for its entire movement, so its entire movement needs to occur within range. The Rock of Extended-Range would then not be valid, because I can only control the rock while I am touching it. However, this is contradicted by certain spells such as Commanding the Harnessed Beast (p.120) and Gift of the Frog's Legs (p.134) and The Walking Corpse (p.135) which have range Touch and then exert influence over the target's actions over (any?) distance for the spell duration, even out of sight.
So:
If range is the range an effect can extend into for the duration, then all Touch spells should end when the caster walks away from the target, and clearly they don't, so that can't be the case.
But if the range is only the range to the originally affected entity, then Wielding the Rock of Extended-Range is valid, and contrary to the spell wording, Wielding the Invisible Sling should be able to strike targets beyond Voice range.
If the range is the range at which the caster can continue to exert control for the duration, then spells like Commanding the Harnessed Beast are invalid (unless it's intended the caster walks arm-in-paw with their servant animal while it does its task...).
You can cast the spell at Touch range, but at that point you need an aiming roll,as you no longer have the degree of fine control over the rock as it moves to guarantee an auto-hit. The spell you're describing is essentially "Invisible Sling of Vilano" as per page 38 of Houses of Hermes: Societates.
See "The invisible sling of Vilano" from Houses of Hermes:Societates - this spell fires a rock you are touching, but because you are doing it at touch range, you have to aim it (with 20 pace range increments), and this allows you to avoid having to penetrate magic resistance by aiming.
"Wielding the Invisible Sling" uses magic to target all the way, so it hits targets automatically, but needs to penetrate magic resistance as it's guided by magic.
And it suggests the range is always range to the affected instance of Form, and the range at which you can exert precise magical influence over it for the spell duration, and is not the range to any individual you are attacking or affecting by what you do with that Form. I feel there may be some spells which contradict that idea, but perhaps not... I'll keep any eye out for any, but that satisfies me for now.
Looking at Commanding the Harnessed Beast, it does actually look like you're implanting a command at the point you're casting the spell. There's also this line of page 111 of the core book:
A spell that has a continuing effect remains in effect even if the caster moves out of range. A spell that allows the caster to control the effect only permits that control as long as the caster is within range. However, it does not expire if the caster moves out of range, and he may control it again if he moves back into range.
That said, it wouldn't shock me if there are some spells out there that give more leeway. I'd be inclined to view them as errors (/unusual effects due to experimentation), though.
You also have to take into account the Target, which can effectively increase your range. What I mean by that is as long as you are within Range of some part of the effect, you can still control all of the effect. This really only applies to large Targets which are effectively area of effect. So things like Room and Structure are the most obvious. A target of Individual with several Size modifiers would also let you do things beyond what your Range would seem to initially allow.
Target: Group requires more care since it is multiple individuals. So a Range: Touch, Target: Group spell means to cast/control it you would have to be touching each individual, with a possible exception being that they could chain the contact (meaning casting is touching A, A is touching B, B is touching C, etc).
If you cast a Range: Touch spell with Target: Room or Target: Structure, you can control the effect as long as you are touching the Room or Structure, even if you are not directly touching the thing being affected (as long as the thing being affected is in the Room or Structure).