Also keep in mind that, as the rock-tethered spell isn't intelligent, you probably cannot coordinate with it, and so it will need to win on penetration.
Well, I'm gonna have to annoy a few merinita and steal their inner mysteries' special durations it seems.
That or using hermetic thaumaturgy (dont remember the name, from HMRE) To conjure spirits and help my ambitions of placing 2+ metamagics on a single spell.
Kinda sad that THE metamagic lineage of the Mercere can't do it, at least not without breakthroughs, I'll probably homebrew a somewhat lenient approach and see what my GM thinks
Or just work with a friend if you want to stack MuVi. But there are solo, non-Mystery ways to effectively pull it off. Flexible Formulaic Magic, Mutantum Magic, and Boosted Magic will all let you combine their own adjustment with a MuVi. But, yes, that Mystery will work, too.