Alliance Gold pile

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Just a thought, rather than have one person pay out the total 600 gold to add additional parties to your alliance, maybe add a gold pile that members could contribute to as they complete challenges.

That way someone isn't dumping a whole 600 gold into getting another alliance member and if you are obtaining gold slowly you can see the progress as you each add additional gold.

Could also result in a membership due for your alliance (every month they deposit 25g into the alliance bank to increase the alliance size, etc).