If I had to guess, it's the tech floating chair guy uses in Ala Mhigo to rip out our souls, then the Ascians messing with it to throw us into the first reflection and see first-hand the damage that foiling their plans would do.

I'm like 99% sure Garleans are involved, especially considering every Scion was affected... every Scion but the one who's been presumed dead by the empire and we see is fine at the end of the MSQ.