Charity Trophy?

[Huggz]

I think a restriction would need to be put in place that at least one member of group/duo would need to have not previously completed the challenge. Otherwise trophy farming could become problematic, particularly in duo's as a lot of players have alts. Might be necessary to create a steeper scale than just 10 challenges, at least the further along you get.

This might not be a bad incentive to get more than just the good will helpers in challenges.