All healing critical strikes now heal for 2 times a normal heal (+100%), up from 1.5 times a normal heal (+50%).
Buffs
All class abilities which place a buff on friendly targets no longer generate any threat. This goes for raid-wide buffs like Mark of the Wild and Power Word: Fortitude, as well as triggered effects such as Blessed Resilience or Fingers of Frost, and single-target buffs like Dark Intent and Hysteria. The exception is buffs which directly cause healing or damage, such as Thorns or Renew. Abilities such as these still generate normal threat.

Pets
The Aggressive pet stance has been removed and replaced with the Assist stance. This stance will cause the player's pet to attack the player's target. The pet will not change targets unless the master attacks a new target for a few seconds.

Spell Interrupts
When interrupted while casting a single-school spell such as Mind Flay or Frostbolt, players will now be able to cast dual-school spells such as Mind Spike (Frost and Shadow schools) or Frostfire Bolt (Frost and Fire schools). However, being interrupted while casting a dual-school spell will still interrupt all respective schools as intended.

Death Knight
Obliterate base damage has been reduced to 150% weapon damage, down from 160%.
Frost
Annihilation now increases Obliterate damage by 12/24/36%, down from 15/30/45%.
Unholy
Unholy Might now increases Strength by 10%, up from 5%.

Druid
Ferocious Bite damage has been increased by 15%. In addition, its base cost has been reduced to 25 energy and it can use up to 25 energy, for up to a 100% damage increase.
Mangle (Cat) damage at level 80 and above has been increased to 530% weapon damage, up from 460%.
Omen of Clarity clearcasting buff from now lasts 15 seconds, up from 8 seconds.
Ravage damage at level 80 and above has been increased to 975% weapon damage, up from 850%.
Shred damage at level 80 and above has been increased to 520% weapon damage, up from 450%.
Swipe (Cat) now deals 600% weapon damage at level 80 or higher, down from 670%.

Balance
Insect Swarm now generates 8 Lunar Energy for Balance druids.
Moonfire now generates 8 Solar Power for Balance druids.
Sunfire now generates 8 Lunar Energy for Balance druids.
Earth and Moon's duration has been increased to 15 seconds, up from 12.
Fungal Growth spell visual effect has been updated to be less visually intrusive and more aesthetic.
Lunar Shower has been redesigned. When casting Moonfire, the druid gains Lunar Shower. Lunar Shower increases the direct damage done by Moonfire by 15/30/45%, and reduces the mana cost by 10/20/30%. This effect stacks up to 3 times and lasts 3 seconds. While under the effects of Lunar Shower, Moonfire generates 8 Solar Energy, and Sunfire generates 8 Lunar Energy. The amount of Lunar/Solar Energy gained does not change based on the number of points spent in the talent, or stacks of Lunar Shower. Those druids who wish to delay transition in or out of an Eclipse state should now cast the one of their two basic attacks which will not move the Eclipse bar (either Starfire or Wrath).
Solar Beam has a new spell effect.
Wild Mushroom: Detonate can now also trigger Earth and Moon, in addition to Starfire and Wrath.

Restoration
Symbiosis (Mastery) has been removed and replaced with Harmony. Harmony increases direct healing by an additional 10%, and casting direct healing spells grants an additional 10% bonus to periodic healing for 10 seconds. Each point of mastery increases each bonus by an additional 1.25%. Healing Touch, Nourish, Swiftmend, and the initial heal from Regrowth are considered direct healing spells for the purposes of this Mastery. All other healing from druid spells is considered periodic.

Glyphs
Glyph of Berserk duration increase is now 10 seconds, up from 5.

Hunter
Multi-shot damage has been reduced. It now deals 120% weapon damage at level 80 or higher, down from 137%.
Traps now scale with hunter stats such as hit, expertise, spell penetration and attack power as intended.

Mage
Spellsteal now has a 6-second cooldown.

Paladin
Divine Light mana cost has been increased to 35% of base mana, up from 30%.
Flash of Light mana cost has been increased to 31% of base mana, up from 27%.
Holy Light mana cost has been increased to 12% of base mana, up from 10%.
Rebuke, Divine Shield and Divine Protection have new icons.

Holy
Holy Shock mana cost has been increased to 9% of base mana, up from 8%.
Speed of Light now increases movement speed when Holy Radiance or Divine Protection are cast. In addition, this talent now reduces the cooldown of Holy Radiance by 13/26/40 seconds, up from 10/20/30.

Protection
Ardent Defender has a new spell effect.
Hammer of the Righteous mana cost has been lowered to 10%, down from 12% to match Crusader Strike.
Judgements of the Wise now procs on attempt rather than on strike, which means judgements that miss can still grant mana. This is to help ensure Protection paladins are not starved for mana if they aren't capped on hit rating.

Shaman
Lightning Shield and Water Shield can no longer be dispelled.
Unleash Elements is now in the Nature school, and thus can no longer be used if a shaman's Nature school has been locked out.
Water Shield has had its internal cooldown reduced to 3.5 seconds, once again matching other shields. The amount of mana restored when Water Shield procs has been reduced by 50%.

Elemental
Lava Flows now grants a 30/60/90% haste buff when a Flame Shock effect is dispelled, up from 10/20/30%.
Thunderstorm now reduces the movement speed of players it knocks back by 40% for 5 seconds.

Restoration
Improved Water Shield has been redesigned and renamed Resurgence. When Water Shield is active, Resurgence causes critical direct heals to restore mana (Resurgence rank 2 is roughly equal to 150% of the old Improved Water Shield value when a Healing Wave or Greater Healing Wave critically hits, and scaled down accordingly for faster or multi-target spells).
Mana Tide now grants 200% of the caster's Spirit, down from 400%.

Glyphs
Glyph of Unleashed Lightning (new Prime glyph) allows Lightning Bolt to be cast while moving.

Warlock
Soul Harvest has a new spell effect.

Dungeon & Raids
The Firelands, a new 10- and 25-player raid, is now available for limited testing. Please visit the PTR Discussion forum for the latest raid testing schedule.

Guilds
The daily guild experience cap has been increased by 25%.
The weekly guild reputation cap has been increased by 25%.
The guild experience cap is now removed at level 20, down from level 23.

Items
Darkmoon Card: Hurricane damage done when triggered has been increased by 40%, however, it can no longer deal critical strikes and no longer receives any modifiers to its damage from the equipping player.

Set Bonuses
The 4-piece Elemental shaman PvP set bonus (Gladiator's Thunderfist set) has been redesigned. It now causes Lightning Shield to generate an extra charge, rather than consuming one, when it is triggered by receiving damage, up to a maximum of 3 (9 with the Rolling Thunder talent).

Professions

Skinning
Players can no longer skin corpses already being actively skinned or looted by other players.

PvP
Conquest Points
The minimum cap on Conquest Points earned per week is now 1500 at 1500 or less Battleground rating. The maximum cap remains 3000 at 3000 or more Battleground rating. The cap continues to scale non-linearly between those two points.
The game now separately tracks different Conquest Point caps for Battlegrounds and Arenas. The cap for Arena rating will always be 2/3 of the cap for Battleground rating at any given Arena rating. Players may earn a total number of Conquest Points per week equal to the higher of these two caps, but once players have reached the cap for either Arenas or Battlegrounds, they can no longer earn Conquest Points from that source. Conquest Points from Battleground holidays only count toward the total Conquest Point cap.

Quests & Creatures
There are no longer oddities in the critical strike and dodge chance of lower-level creatures.

User Interface
Raid Profiles are in the process of being implemented and are not fully functional. Raid Profiles will allow players to save the raid window user interface layout based on type of content (i.e. 10-player raids, 25-player raids, Battlegrounds, etc.).