Hi,
I first like to say apologies for reply to my own post, still it is relevant to initial post so here goes, since, apparently you are considering a "shield" like system, wanted to add a followup suggestions, if shield had x health points to it before it is destroyed, could use the speed, from first to last damage point, to calculate boss health and loot, for example say for each 10 seconds to bring down 5000 health shield would lower boss health by 500 and lower total loot by 5, making it the focus of all players to do as much damage as possible to get a better chance of challenge and loot later, could also allow players to take their time if most wanted a easier fight.
I also have to make note that the random event system is not working, in my opinion, making it harder for players to take time to log on, having tiny chance to be on when the one event they are after comes up, than if was fixer timer or other alternatives, like "debuff" suggestion that made in other post, to allow players to still have chance at events they are after even if logging on once a day,
Thanks.