Instead of guilds individually battling their own raid boss, how about having raid bosses appear at scheduled timings that allow all guilds to participate?
Mechanics and Rewards:
* Use 5 stamina to join
* Raid boss to appear 2 or 3 times a day to cater to different time zones
* Event lasts 30 minutes. If the boss escapes, no one gets the final rewards.
* Participants get xxx gold for each xxxx damage, awarded immediately after each hit
* Top 3 or 5 will get final rewards
* Random drops for players at predetermined ranks (e.g. 6, 16, 26, etc). This ranking should change with each scheduled raid boss.
* Last shot bonus for player whose hit killed the boss
I'm not getting paid for this so I shall not elaborate further. Let the developers chew on this and work out the details.