Maybe they should tweak the current titan system a bit... some titans are kept alive for weeks because of the +50% kill goal... .I do not think there should be a cooldown for titans if a guild buys the epic item. That way the titans would be killed a lot faster than now is the case. The cooldown for a +50% kill may be kept, I do not see issues with that.
And maybe the cows could introduce a new kind of creature. There are a lot of games nowadays that throw in special events like spawning one big ass creature with a huuuuuuuge health point stat for a couple of hours and the rewards are then divided according to the percentage of contribution either by player or by guild. Those events are obviously announced way ahead so people can save up some stamina for it.