How I would make the next raid better,
Give the boss unlimited HP. This would allow everyone a chance to use all of their characters in a raid without worrying about killing the boss to soon and my fellow guild members not getting an attack.
Give the raid a time limit. 48 hours seams fine.
Your guild would defeat the boss if they can do a combined total of “X” damage by the end of the time limit.
Could possible give everyone that contributed to the raid better rewards if not only did your guild do “X” damage but you group hit the hard mode of “Y “damage or even a third tier of “Z” damage.
I understand having multiple phases in a raid as an attempt to keep things interesting, however I would remove them. They just create imbalance as players with weaker teams can outscore stronger teams just because the lucked out and attacked in a different phase.
Just my 2 cents.