Since you can Master a ritual, hypothetically the Mastery can be multi-cast.
Assuming that you have enough Vis, what rituals does it make sense to multi-cast?
A double layer Aegis of the Hearth doesn't double any benefits, does it?
If you had your Talisman at a distant location and some sort of Intangible Tunnel, perhaps you could cast both sides of a Hermes Portal ritual?
Multiple healing rituals?
ArMDE 07-Hermetic Magic spells out, that you can save significant Vis by multiple casting Rituals mastered for this. But as you cast every instance separately, you might collect fatigue by the tough table for Ritual magic multiple times - and excess fatigue levels convert to wounds as usual.
In general, a maga might choose between inventing a T: Group or static container Target (ArMDE 08-spells) booster ritual, or inventing a similar T: Ind ritual and then master it for multiple casting.
Multi-cast instant creo spells for when you have to create lots of materials? Conjure multiple mystic towers at once?
The characteristic boosting rituals from the cult of heroes in the Mercere section of HoH:TL would be ideal for multi-casting, as players always want as many boosts as they can get.
The Multiple Casting spell mastery says:
"This special ability may be taken for Ritual spells. The casting time is that for a single spell, but one pawn of appropriate vis per magnitude of the spell must be expended for each copy. The normal limit on pawns of vis expended (the maga's score in the Art) applies"
So that's... not a savings of vis at all for multi-casting a ritual. You're spending one pawn per magnitude for the ritual as normal, and one pawn per magnitude for each copy. I suppose it would need a house rule that the multi-cast copy of a ritual counts as a ritual for purposes of Mercurian Magic or Root-Cutter to get the same vis-cost reduction, since it's not spelled out here.
You'd save significant vis (and fatigue) by inventing the T: Group or container version of the ritual, where you're only paying the vis surcharge for the difference from higher magnitude instead of paying for the entire magnitude for each copy.
Right. And that makes multiple casting for Rituals an extreme niche.
Not sure you can use the "Group" target to create multiple copies as typical creation ritual create a mass of things so it would make a bigger tower instead of multiple seperate towers for example.
I can see a magi specialized in say Aegis have quite a high mastery level of the ritual and at some point, will master multicast. It might be useful in certain wizard wars where you want to layer quickly a few of them knowing that it takes a round to bring them down... still a few extra rounds could make a difference.
W
Am pretty sure he meant for healing rituals, and the rituals to increase characteristics
It would be more logical to use a container-type Target for healing Rituals and stat-boosters and such, but there's nothing preventing a wizard from creating a Group Mystic Tower ritual if for some reason he or she wants ~10 identical towers in very close proximity. Seems a bit niche but it'd make for an interesting covenant.
Magnitudes to multiply Individual size are distinct from Group; you can apply both. If, for example, you wanted to conjure 10 elephants adding Group + size Magnitudes wouldn't just get you one very oversized elephant.
Sure you can. See Boundless Wealth of the Oceans (Transforming Mythic Europe, 117), Fill the Capacious Silo (Transforming Mythic Europe, 120), The Riches That Are Rightfully Mine(d) (Covenants, 61), The Apple That Etches (Covenants, 96), Plant the Bountiful Feast (Magi of Hermes, 75) . . .