Hmm, somehow I'd gotten it in my head that it was a 2. Not sure how I managed that.
So, a PeTe spell to fragment the stone so that the mundanes will ahave a much easier time removing it. Lothar proposes to do this under the guise of heating up the rock with a fire then colling it abruptly with water.
PeTe Base 2: Weaken dirt, +1 Touch, +1 Part, +1 for stone, +1 Size (for 10 cubic paces affected). Total level is 10. Casting total is 13 (Int 2 + Pe 4 + Te 4 + Aura 3) or 14 (if he spends 30 minutes preparing the spell as a ceremonial spell).
I am assuming that if the spontaneous casting is short of the target level, it is the Size increase that will be dropped. I am also using only a single botch die.
The first time Japik casts the spell, it feels like something is resisting his attempt to weaken the stone. This destabilize his magic and he loses control of the spell. (Botch!) But as the circumstances were reasonably stable, this doesn't send him into Twilight. Still, he gains 1 point of Warping.
Does he continue? I would assume that he does, but I want to make sure before I roll again. Or you could use a dice-rolling site like Invisible Castle to make the other rolls. I don't mind in this case. 
Wow a botch immediately! Invisible Castle doesn't work, at least not for me today. I can't find any other online dice rollers where you can copy paste the result in here. Does anyone know of any?
In the meantime roll away, Arthur. Japik is not one for risk-minimizing.
Only stop if there is another botch or he gets too fatigued.
Not that it matters much here but isn't it Stamina instead of Intelligence to calculate the Casting Score? So 15 before stress die.
I've had trouble with Invisible Castle as well.
coyotecode.net/roll/ is what I've been using lately.
Indeed, that's why I stopped before continuing. 
Remember to update your magus' stats to add the warping point gained.
Indeed, corrected my previous post.
Am I right in assuming that is not casting ceremonially (i.e. taking 30 minutes each time)?
Second and third spells are cast successfully, although he still feels that there is something wrong going on here. It still seems like there is something resisting his magic.
At that point he is Tired (-3) and must rest.
I have updated my stats with the Warping point.
He doesn't cast ceremonially.
After the third try he tries to cast Unseen Arm (ReTe5) just to try and see if he can feel a resistance to his formulaic magic as well. He uses it to move some small rocks or other light object just to see how it works.
Unseen Arm seems to be working normally... there is no sense of resistance when he casts it and no diffuculty in moving rocks around using it.
When is this taking place with respect to Konrad's arrival?
I believe this is early summer and Konrad arrives late summer?
Yes.
Japik rests then he tries to cast the Weaken Stone spell ceremoniously to see if there is a difference in resistance then.
After that he will consult Prochorus and Herman.
His fourth casting faces the same resistance as before. The spell is only strong enough to affect 1 cubic pace.
(Just to keep track, so far he efforts have covered 21 cubic paces.)
When this is mentioned to Herman, he has two thoughts. He mentions both, as they may be related. One thought is that there is a Pe-resistance in the mountain. That would be rather interesting. If true, it would seem to be an indicator of something larger. The other thought is that the magic resistance is tied to the solid rock, so once a piece is broken off there would no longer be resistance. One way to check this would be to try a PeTe spell on one of the smaller rocks that has been broken off.
Japik's thoughts are about the same. That there is something bigger perhaps connected to the oak tree or the ground itself. He tries to spont a simple PeTe spell to get some small pieces of rock to disappear.
Destroy Dirt is Base 3, +1 for Stone and +1 for Touch, Total level 5. He tries it on a small piece from the rock no bigger than it is possible to lift in one hand.
The sea has perdo terram magics all its own. Maybe this resistance is why this rock survives in the first place. Something similar with the pillars out there?
The spell succeeds, but faces the same problem. To Japik, that resistance feels familiar somwhow. Some thing that nags his thoughts in the following hours, until it hits him. This seems like a weaker version of what one feels like when casting a spell inside a foreign Aegis of the Hearth!
"There is in deed some kind of innate protection in the rock." Japik tells the other magi. "It feels like a weak Aegis of the Hearth. I wonder how long it stretches, and what is causing it. Could it be connected to the oak tree?"
OOC: Maybe this is the wrong thread for IC posts. It's just that we started playing out the spellcasting on the rock here.
I (Herman) will attempt a spontaneous Intellego Vim (base 15In+5Vi+2Sta+Aura+Stress Die) to see if I can detect by touch magic in the rock. (Base 5 to detect active magic, +1 for touch range, momentary, and I believe it counts as an individual target. So it should succeed on anything other than a both.)
(Herman can detect no active magic in the rocks.)
(I'd like to clarify when this is happening and who is present. The initial casting of the rock-breaking spells were probably planned to happen late in the evening, when the workers were finished with their day's work. Do these investigation happen later at night, or is it during the next day? Did all the magi come by at the news that something strange is happening? Or is it just Japik working on the spells and Herman because he is working in the lab?)
Herman would do this as soon as he is told of the oddity.