Perpetuance doubles the duration of the next Enhancement spell cast.
Immanence allows the creation of level 1 and level 2 SCs, both opening and closing. 2 charges are required to SC (1 charge each spell).
eg. Immanence + Blizzard -> Immanence + Water = Fragmentation.
I imagine it would be difficult to solo SC using high tier magic (IV/V) due to casting times correct?
Correct. Either Alacrity would need to be used or it would not be possible at all.
The initial testing (Blizzard => Water) had Immanence + Alacrity up for the 2nd spell, but I get the feeling you could get away with not using a charge of Alacrity.
One could ultimately SC with themselves and MB, but whether or not the MB is practical with the higher tier spells remain to be seen (it should be easy to do with Helices, though).
Perpetuance seems to have different behaviour with spells
With RR and most of static buffs > time + 100%
With sneak & invis it seems that's more since i tried this in abyssea altep and my SN/I wore off after 15-16 mins (mostly 15 ... timer stops when triggering a Veridical conflux)
It's truly an awesome Stratagem
Extra : It seems that Perp is spread when combo'ed with accession among every targets ( even with adloquium)
They did change Sneak and Invisible's max duration and duration variance this last patch, did they not?
Scholar, Monk, Black Mage