I have recently been working on a BUGBprophet of kruphix shell, that uses cards like reaper of the wilds, desecration demon, prognostic sphinx, and aetherling as win conditions.read the bones is great card draw, and syncopate is just good with prophet of kruphix. I just have one problem with the deck. I have found that in the late game, I have all this extra mana, and nothing to use it on. What is a good, reusable mana sink in these colors?
I haven't played much with Prophet decks, so it's hard for me to say, but have you considered adding some card draw? If you have lots of open mana and not enough spells to cast with the mana, casting something like Opportunity might help you get to more of your spells. That's just an idea though, someone with better knowledge of this type of deck could probably be more helpful.
BUG has very few mean to correctly use prophet unlike Bant which can sink it mana into sphinx rev or urban evolution.
Altougth one way you could use prohphet well would be in a shell using Whip of erebos / Grisly Salvage / Commune with the god allowing you to use whip for creature attack grisly/commune for card fetching/advantage and keep the untap part on next turn (aka enemy upkeep) for either flash card or counter spell.
If you want a specific outlet for Prophet then Zameck Guildmage is probably one of the best. His first ability stacks for however many times you can afford it and his second ability draws you into things for using with Phrophet.
Golgari Guildmage can get there. All the guildmages work very well with prophet.
Altougth one way you could use prohphet well would be in a shell using Whip of erebos / Grisly Salvage / Commune with the god allowing you to use whip for creature attack grisly/commune for card fetching/advantage and keep the untap part on next turn (aka enemy upkeep) for either flash card or counter spell.
Another way could be a Varolz engine.