Ritual conjuring, More group magic Options

[Tanegar]

SR4A has rules for group sorcery and group initiation, but not for group summoning. That seems like a pretty major oversight to me. Groups of wizards/sorcerors/what-have-you summoning enormously powerful entities are a staple of fantasy tales. I'm going to take a whack at cooking up some house rules for this, based on the ritual spellcasting rules; take a look and tell me what you think.

Requirements
As in ritual sorcery, all members of the ritual team must be of the same tradition. The ritual must take place in a magical lodge appropriate to the team's tradition, and the Force of that lodge limits both the number of magicians who may participate and the Force of the spirit that may be summoned. Unlike ritual sorcery, where the Force of the spell can be no higher than the Force of the lodge, ritualists may summon a spirit of up to double the Force of the lodge; i.e., a Force 4 lodge allows the summoning of up to a Force 8 spirit. The size of the ritual team is further limited by the lowest Ritual Summoning (note that this is a new skill) rating among the members; to adapt the example from the book, Harry, Al, and Rowan have Ritual Summoning skills of 3, 5, and 4, respectively. Their Force 4 lodge would allow one more member to participate, but Harry's 3 skill rating precludes a fourth member from joining.

Team Leader
Each ritual summoning team must have a leader. This is normally, but not necessarily, the most powerful or skilled magician. The leader's Ritual Summoning + Magic forms the basic dice pool used to determine the ritual's success; the leader's Magic attribute also limits the Force of the spirit to be summoned. The ritual team may summon a spirit whose Force is up to the team leader's Magic x 2. If Al is the team leader, and his magic is 5, he could potentially use a ritual to summon up to a Force 10 spirit; note, however, that the limit of the lodge's Force is still in place. Because Harry, Al, and Rowan are only in a Force 4 lodge, they can still only summon up to a Force 8 spirit.

The Ritual
Ritual Summoning is performed in the same manner as regular Summoning, except that the ritual takes a number of hours equal to (12 + spirit's Force - team leader's Magic). If Harry, Al, and Rowan are summoning a Force 8 spirit, the ritual will take them (12 + 8 - 5 = 15) hours. When the ritual begins, the dice pool is equal to the team leader's Ritual Summoning + Magic. Each additional member of the team makes a Ritual Spellcasting + Magic test; their hits are added as a dice pool bonus to the leader's pool, as per the rules for Teamwork Tests, p. 65 of SR4A. Individuals may use foci to supplement their own tests.

Noticing Ritual Summoning
There is a chance that any being capable of astral perception within (Force of the spirit being summoned x 100) meters of the lodge may notice the change in the ambient mana. The gamemaster makes an Assensing + Intuition (20 - spirit Force, 1 hour) Extended Test for each such being beginning one hour after the start of the ritual to determine if they notice anything unusual. In extreme cases (GM's discretion), there may be signs noticeable in the physical world; i.e., summoning a high-Force fire spirit may cause all flames within (Force x 100) meters to burn blue for the duration of the ritual.

Ritual Drain
At the end of the ritual, each member of the team must resist Drain equal to twice the hits (not net hits) generated by the spirit on the Opposed Summoning Test (minimum 2 DV). This applies whether or not the team leader generated any net hits in the Summoning Test - that is, whether a spirit appeared or not. For the purpose of the determining whether summoning Drain inflicts Stun or Physical damage, add the Magic attributes of all the ritual participants together; i.e., Harry's Magic is 3, and Rowan's Magic is 4, so they and Al (Magic 5) cannot summon a spirit powerful enough to inflict Physical Drain damage (Force 13 or higher).