wizard's communion and parameter variation

I'm french fanplayer of arm5th and I 'm wondering about the Wizard's communion utility. A group of magi has recently use this spell to change the target of a spell: One of magus has the spell " lungs of the fish" (mu aq-au 20/ CRp122) which is a personal spell. The magus would affect an extended group of 30 person and so increased the level to six magnitudes to perform it. Its means the communion is used like the wizard boost, but allows a group of magi to participate.
it is conceivable that the wizard's communion allows this feat or is this an heresy?
thanks for answers!

Well, the first rule is always: if you do not like the Rules As Written (RAW), change them to have fun.

That said, Wizard's Communion works differently according to the RAW. Basically, a Wizard's Communion with N participants allows the leader of the Communion to cast a spell of level X as if it were a spell of level only X/N. For example, the leader of a Communion with 5 wizards treats a level 50 spell as if it were only a level 10 spell. Vis costs are not affected, and the leader must still know the spell (or cast it from an a casting tablet). This allows a Communion to cast very high level spells, and to do so with decent penetration -- it's particularly useful for Aegis of the Hearth.

Be sure to read the errata on MuVi!

WC cannot change the R/D/T of a spell.

Since the basic group version of Lung of the Fish would be MuAq(Au)30, you'd need a MuVi30 Wizard's (Range+1 Target+2) Boost (Aquam) to have it affect 10 targets in a single cast. Assuming you can cast LotF(R:Personal) as a Formulaic spell.

If you don't know that MuVi30 Wizard's Boost (Aquam), you would have to cast it as a Spontaneous spell and require a roll of 60+. WC specifically states that it does not work on Spontaneous spells. If it could and 3 magi used WC, that roll would go down to 20+.

Note that Wizard's Boost last sentence allows spontaneous spells to be extended to ritual-only R/D/T when using a ritual version of WB. Which should supercede MuVi Guidelines (2nd para) "cannot be cast on spontaneous spells." YourSagaMayVary.

I guess the flow of the game was more important than RAW here.

great thanks for your answers!