Here were all the changes people found:
Lucifron - 4 adds, up from 2. Encounter mobs still double HP. Adds might extend curse as well?
Magmadar - Mag is the wall. 2 dogs spawn 30 seconds in, and 2 more every minute afterwards. They all have the smolder mechanic.
Gehennas - 4 adds, up from 2 (CURRENTLY BUGGED: Will link the fire lord on the left side). Rain of fire seems to last longer. Adds may be more stun happy. Healing rebuff still in.
Garr - Small adds spawn that detonate and knock back nearby players. At a certain point (unsure if health or time based) all adds become cc immune. Garr is much more likely to explode his adds now.
Geddon - 3 bombs instead of one. Bombs leave a bad patch (250/tick). Inferno leaves a big bad patch (1k/tick). Armageddon is chain casts and looks to get a 50% haste buff on each cast. Mana burn still in.
Shazzrah - now leaves a 45k hp clone at the spot tele’d FROM, that spams arcane explosion. Now taunt immune. All other mechs still in.
Sulfuron - Shared HP pool with all adds. Heal doesn’t scale correctly (Likely a bug), inspire now makes adds hit like trucks. Significantly undertuned.
Golemagg - Adds keep buff regardless of distance. Small earthquakes throughout the fight. Stacking debuff from melee now matters.
Domo - Elites fireball volley. Adds might be CC immune at 2 deaths instead of 4. All other mechs in place.
Rag - Forced submerge @ 50%. Sons start P1 spawning at 30%. Felt like more Sons on second submerge but likely just the P1 spawned adds. All of their mechs still in play. Hour timer still in play.