I'll run you down the majority of the fight along with how to fight. The chances of you actually finishing Tiamat's Temple are below 25%! The reason for this being that there are a major amount of elitists in the community who will not so much as try to do anything if there is so much as 1 person with a GS lower then 20,000. You will get items from Tiamat ranging from commons (white) to Epics (purple/violet) even if you LOSE, BUT you will not get your Tier items IF you lose. Plus there's a weekly quest for killing Tiamat that puts people off donating their coins and coffers as well, but you can get and convince people otherwise if you get those tiers up.
I never even think about donating unless I have 500 coins or more and at least 50 coffers. The only problem is making that happen, so you really do want to stock pile your Coins and Coffers. The higher the tier, the less likely people are to leave and really output their best D/HPS (Damage/Heals Per Second.) The reality is anyone who has entered the Well of Dragons is able to fight Tiamat.
These two items are the currency in which you can level up the Contribution Tiers for Tiamat's Temple. Why is it you need to do these four things? Simple yet again, you need Dragon Hoard Coins and Dragon Hoard Coffers.
