First let me say that i respect the thoughts and the work you put into creating this spell.
Its well-thought out - drain, boni and even the disadvantages fit very good together.
But i do have a suggestion about the indirect spellcasting.
Reading Clairvoyance and Borrow Sense make me believe that the devs don't want to grant us the indirect spellcasting at all. Meaning one should not be able to cast
through pack members.
But considering the fact of
shared consciousness and that the mage wouldn't shift his sight to a new point of perspective, but instead actually gain a new kind of direct sense to
see the target, i would still consider it direct spellcasting. The -3 modifier is still reasonable though, but you wouldn't need the negative essence modifier.
Also you implicitly used the Extended Area option, while a normal version with 2 less drain and maybe average 20 meter radius is a very viable option.
then you'd know there aren't any actual rules for "hacking" psychic communications, so if it's going to be possible at all it's going to be a GM's Discretion situation.
Sorry to go slightly off-topic here. There a indeed no actual rules for psychic hacking, but for me the FAQ has as much merit as any other book, as long as it is not contradicting. In the books hinted and in the FAQ further explained is the possibility to eaves drop on psychic communication. For that you have to be a projecting mage and use "silent" manifestation near the target. But yes, it will still be up to the GM how this will work.
