The CoP Ancient Vows Mission can be found here:
http://mysterytour.web.infoseek.co.jp/ffxi/us/mission/04cop.htm

It was my hope to attempt two tries of this Mission in one CoP Monday Evening but one try at the three Mamet-19-Epsilons consumed four hours (the Mission ended at 12:30am on the East Coast). For Ancient Vows you essentially buy out the Jeuno Auction House Medicine Cabinet and throw it at the Mammets.

Maior has pointed out that for CoP runs to Spires the Event Reward: Charm Wand and the Charm Wand +1, are nice to have within your party. For such Events, and for Mammet Fights, the Charm Wand alone is probably worth about 60,000 gil since that is the cost of a Re-Raise earring.