There's only one change to the Ula'tek encounter which is a large change for big group sizes.
Spectral Coils no longer scales its damage with group size on Normal and Heroic
On Heroic difficulty, the Spectral Coils ability does ~680k damage at a baseline. There was a multiplier on this ability which made it scale by an additional 10% per person, scaling up to 200% bonus damage at 30 players. This would make sense if it was a normal soak ability, but that is not how the ability works. This ability is different in that it doesn't split the damage evenly per player, but instead each player just reduces the amount of AoE damage. This means that a 10 player who reduces the damage by 50% would take 340k damage, while a 30 player raid who reduces the damage by 50% in a similar way would take 1 million damage. That's a pretty big difference and why this ability no longer scales with raid size.
