Hoping to pick the devious minds of my fellow SGs.
Setup: a Hermetic Covenant has a restricted access, that they can roll a large boulder down through unwanted guests.
But how do they get the boulder to go back to the top ie reset the trap?
I am assuming that the boulder is non-magical (to get people and creatures with MR). Also boulder is big enough that a dozen Str +5 characters would struggle to roll it back uphill.
How would your magi do this?
Set up a ReTe teleport with an automatic trigger aiming at where the boulder would land, to send it back to the top of the trap.
What causes the ReTe effect?
I requested that the boulder itself not be stopped by MR
Sisyphus' Need - a glove (with bronze studs?) with a R:Touch, D: Concentration effect that temporarily destroys the weight of the boulder (a base PeTe 5 guideline), allowing it to be rolled back up the hill by a single grog? (base 5, +1 stone, +1 Touch, +1 Conc, +x Size, +uses per day)
I see: you request an automatic reset.
Once the boulder has come down, broke something, perhaps got stuck where it shouldn't, this provides many interesting ways to make a reset mechanism do things it wasn't meant for.
Was that the purpose of the OP? 
The boulder is non magical just a plain lump of basalt cut to into a cube of just under 2 pace per side.
By default, it is resting in a 2 pace per side cubical "void" above the trap plate.
The trap plate is a 2 pace square slab of granit that is part of a corridor with identical looking slabs making the whole path seem normal.
The trigger slab is enchanted with 2 effects:
InTe, Detect when stepped upon when stepped upon by a person not carrying the Covenant's Aegis token,
PeTe, linked effect, which triggers a Diam duration PeTe (part) spell which temporarily destroys the ceiling above it in a 2 pace square. So at th end of the effect, the ceiling is intact again and nothing is visible
The Corridor (shape Hallway) is enchanted with a every diam, the slab will automatically teleport any basalt object to the void above (ReTe, touch). Alternatively, an anodine looking (one of the many wooden beams for example) object could be doing this effect, though would need Arc range.
The rock falling is in no way magical and will not be affected by MR, as only it's shaping into a cube will have been done by magic. However, it will weight roughly 10 tones reducing anyone underneath to red mist.
Okay, first of all that is not how a PeTe spell with a duration works- the ceiling would not come back. You would be better off with a CrTe spell with concentration duration holding the ceiling i place where the item maintains concentration unless (trigger action).
Also note that InTe will not detect Aegeis tokens, and the tokens are only given to magical visitors, not magi, covenfolk, or teamsters delivering supplies.
Actually moving the rock back is fairly trivial compared to the rest of the triggers- as mentioned you can simply teleport it back and can use a fixed arcane connection to identify it (not o target it) or embed within it some form of metal-based identification- a symbol or sigil that indicates "this is the trigger"
Considering the broad strokes of the Effect use guideline (Arm p 99):
You may also restrict the use of the device to an undefined group, such as only women,' or ''only people in my direct magical lineage by using a linked trigger.
I don't see why not being a member of a covenant would be harder for the item to figure out than not being part of a magical lineage.
As for the PeTe, I guess I went too much on the basis of Harmless Magic Flaw, which the Te magus in my last game had...
Think the rolling boulder from the beginning of the first Indiana Jones movie, though down a gully rather than a cave.
While "Automatic" would be nice, I was looking for anything quick and doesn't require too much effort.
Jason72's glove idea is interesting.
Other options:
Also, I'd rename Jason's suggested glove to "Dream of Atlas", and make the boulder a representation of the night sky. On that:
From my understanding of MR, the boulder is falling/rolling naturally - if there is a ReTe effect to moveit back to its origin, it will not make any difference to the people being squished. The ReTe effect is not active, so MR doesn't block it.
Once the boulder passes a certain location (or a certain distance), the ReTe is triggered and it moves back to its original location.