I bet everyone of you have an image of what you would like to see in the new operation. The following is just me fooling around, trying to play with basic ideas of MMO's. If you do happend to know the game/raid with such mechanics, please tell me, I would love to watch it on Youtube.
THE SURREAL DREAM - Story Mode
The drained orb
A giant orb in a middle of a large room. The orb is "friendly" and has 100 of 4Mil hp in the begining. The idea is to heal the orb up to 100%.
Fight starts with healers, well, healing the orb. Other raid members can eiter offheal, or kill little "mirage spawns": it drops a buff "healthy" on the player, who delivered a killing blow. The person with the buff needs to get close to orb for it to absord the buff, healing it for 15-20k (numbers can be adjusted).
At 30% **** start hitting the fan. Orbs starts spawning "painful memories" - those thingies get a target with highest aggro (healers, obviously) and go to them slowly, dealing high damage on impact. Can be tanked, upon death heal the Orb. Spawns all the time up until burnphase.
At 50% Orb connects to a random raid members, butting a "drained" buff, draining health from the player. Can be got rid of by killing "mirage spawns". Happens every 30 sec up until burnphase.
At 85% Orb starts raidwise "ticks", with each ticks absorbing hp from raid members. Also drops pools in random location, working pretty much as healing puddles. Helas the raid. Only one pool at a time, raid should stay there, or ticks will be too much to endure.
At last 150k hp (can be adjusted) - "burnphase". Orb gets a timer "critical mass" and should be fully healed until the timer runs out, or in drops 300k hp, dealing massive raid damage.
Dread Master Bestia
Just a normal size arena would be enough.
The key idea of the fight - aggro table. Bestia will ignore it and attack random members, but the key is in aggro management.
The highest and the lowest threat players get a stacking debuff. Upon reaching 10 stacks, they will be stunned and start getting ticks (prety much should be tanks to survive) of fair damage ("anger management"), unless "freed" by other raid members (same as cademimu hm). Freeing generates a large amount of aggro. After they are freed, their stackes ore gone and they're swapped places in aggro table.
Boss itself has a stupid amount of hp. This is compensated with burnphases - after each "release" of the tanks Bestia starts summonning a large sphere of dark energy - being killed before sunnoned, it applies a buff to damage dealt proportionally to aggro on the boss (yeah, so the tanks can enjoy 20k hits. Hell yeah.)
Each taunt multiplies aggro as it should, but grants "LIar!" debuff - large portion of damage. Not a big problem to tanks, massive pain for dps.
Room is surrounded with ancient tablets. Destroying a tablet grants a large amout of aggro to everyone exept the one who destroyed it.
If person's aggro is too low, he gets a "coward!" debuff. It initiates a "duel of fates" with Bestia. If you survive, it puts you on 2nd place from the end in aggro table. The fight is more or less a race with this mechanics - need aggro, not too much to keep tanks on top ond on bottom, but not too low.
"Puzzle" boss
Let's say, we have a standart 4x4 field. Each segment can be one of three colors and grants mobs on this segment a buff:
Red - untauntable
Blue - ad deals more damage
Green - ad receives less damage.
Ads have one of each color and each ad can only be killed on segment of his color! (example: red ad will recieve damage on segment of any color, but the killing blow should be done on the red segment). Upon death, ad drops a "code sequence" of a specific color, which can be carried by 2 raid members at once (like, they have to come together, grab it, and move together to the console)
There are 3 consoles (red, green and blue), each console requires 2 sequences to turn off. Upon consumig a sequence, it resets the field and temporary (15 sec) disables segments of its color (you clicked red console - field is reset and all red segments do not apply their effects for 15 seconds).
As raid progresses through consoles, ads spawn more often, becoming a natural time-length control mechanic.
Should be so much fun.
Please note, that this is just a fantasy, although any of these mechanics brought to life would be totally welcome.
You have your own dreamfight? Please make sure to post it in reply, best ones will make it into this post.