OK, I have been reading all the complaints about how you cannot do a fast casting of a spell to get the hits to cover OR under the SR4A set, and it got me thinking:

Can you use a Sustaining Focus and Ritual Spell Casting to set things up so that you have the necessary number of net hits? Is there a reason this would not be a viable solution?

This is certainly possible but ritual spellcasting takes a lot of time and the spells have the same problems with mana barriers as those cast normally. Also with the teamwork rules you don't generate a lot of additional hits unless you have a large skilled team.

OK, so if you are going to be running into Mana Barriers, your Imp Invis spell would not be working ANYWAY. Besides, I am thinking more how ritual casting turns the casting into an Extended Test, and does away with the total limit on successes of the Force of the Spell

At least according to SR4 without A Ritual Spellcasting is not an Extended Test, the team can only throw the dice once. I can't find a rule that the success limit is waived either.

*hmmms* OK..Interesting..but, yeah..OK, so, you need a ritual group to actually make the Ritual Casting work..but, hmmms....It would still help, and it would give that Mage reason to ahve some magical contacts, or be part of an Magical Group... He gets them to help..gets the 6 successes he needs through the group, and BAM! Improved Invisibility! It really does make contacts more useful....

Edge and a bigger dicepool would be a more reliable and quicker way to do that. BTW the team can also consist of only one mage and his bound spirit, this however does not add extra dice.