@New Mechanics:
Transmutation:
A new NPC has moved into The Chronicon, speak to him to learn about Transmutation!
A ton of new items (equipment, consumables, relics) has been added that can only be obtained through Transmutation
Unlocks account-wide after beating Act 3 on any character (yes, retroactively too)
Damage Stagger:
This is a new stat available to all classes that staggers a portion of all damage taken over 3 seconds
The Berserker has 15% Damage Stagger as base
Damage Stagger is calculated after resistances, Damage Reduction, etc, but before Shields
Damage Stagger stat stacking is multiplicatively calculated, like Damage Reduction, Evasion, etc
Global Damage Diminishing Returns:
Slightly loweres damage of "shotgunning" effects that happen instantly on the same frame, by lowering the damage of each individual hit that frame
Only affects direct damage, so skill procs etc remain unchanged
It's mostly intended as a way to lower the amount of extreme damage spikes on the player, which along with Damage Stagger makes for a more smooth experience without "cheap shots" - especially in Hardcore mode
Radial Looting:
Pressing Q (default, can be changed) now loots all items fitting your filters within your Pickup Radius
Can be set to only loot non-equipment
Dungeon Shady Dealer:
A Shady Dealer may spawn in any area of the game at random, from level 30 and up.. he's got some interesting wares for sale, which will vary somewhat each time you find him
Skill Hotswapping:
You can now hotswap skills from the same skill slot in the skill trees, meaning if you for example picked "Cleave" instead of "Shield Slam", you can swap between them without resetting all points spent
The hotswap can be done by right-clicking the skill in the skill tree (as you would when binding it) and clicking "Swap" instead of a hotkey
Note: Hotswapping will clear buffs and companions just like the Elixir of the Mind does, so you can't hotswap between two different buffs (or ultimates) and use both - it is simply a tool to make rapid changes to your build with little effort
Empowered Shrines:
Shrines may spawn as Empowered, granting two random effects instead of one!
All Shrine spawns are now also randomized between sessions and area resets
@Anomalies:
Removed all narrow cave layouts
Added many new combinations of layouts and locations
@Classes:
Berserker:
Slightly lowered rage generation from taking damage
Doubled minimum rage generation from dealing damage, and slightly lowered maximum
Increased the rate of which Rage fades, and the amount faded per tick
Rage fade is now paused during cutscenes
Now has +15% Damage Stagger as base stat
Warlock:
Soul duration now refreshes when collecting a Soul while at max Souls
Soul fade is now paused during cutscenes
@Enchants:
Added new enchant:
Damage Stagger:
Adds to the new Damage Stagger stat, is considered a Major enchant, and can only be rolled on Helmets, Armors, and all offhands *except* Shields
Changed existing Enchants:
Maximum Rage: 
Max augment is now at +22 Max Rage, down from +30
Mana On Hit:
Slightingly increased augment caps and roll ranges
Can now be rolled on all off-hand items and helmets
Health on Hit:
Can now be rolled on Boots
Evasion:
Can now be rolled on Armor
Damage Reduction:
Can now be rolled on Armor
Effect Duration:
Reach:
Mana Cost Reduction:
Can now be rolled on all Weapon types
Pickup Radius:
No longer rolls on *everything*
Can now only be rolled on Armor, Accessory, Weapon, and Boots
Max Augment lowered to 40%, down from 45%
@Gems:
Kyanite Cube:
While in weapon, now increases mana on hit by 10/15/30%, up from 5/10/20%
@Gameplay:
Zoning now grants slightly less bonus time on killstreaks
Troves now more clearly indicate that they're special by showing a message when opened
Players are now completely purified and healed when killing a boss
HP/MP Regeneration ticks no long happen during cutscens
Hitting enemies mid-spawning animation where they're invulnerable now refreshes the killstreak timer by a very tiny amount
Added some more telegraphing to various skills
Improved the visuals of telegraphing effects 
Added a "radius loot" button based on your pickup radius, default is Q and will loot everything in range according to your loot filters
Does not have a default button for gamepad as we're running out of buttons! But you can bind it in the options if you want. Gamepads will recieve some love soon!
Quest-related NPC's are now always revealed on your map
The "Annihilation" and "Godlike" killstreak meteors now deal damage based monster health and difficulty/anomaly level, rather than player stats
Made many improvements to Click To Move movement based on player feedback:
Can click more freely in void/unreachable areas and character will stil lattempt to move
Can bind skill slot hotkeys more freely without issues (ie all keys on LMB will now work with click to move)
Improved responsiveness and slightly tweaked pathfinding
@Interface & Options:
Added an option to the gameplay menu to pause the game if it loses focus (if you click outside or minimize etc)
Added an option to the gameplay menu to completely remove filtered out items from the game world
Added another option to gameplay menu to allow filtering out equipment from the new Radial Loot thing, so you can use it to grab consumables or materials for example
Updated some item power descriptions to be more clear
Updated damage number visuals to be a bit more clear and crisp
Time played is now displayed in hh:mm:ss, now including the seconds (this also affects tombstones)
Fixed mana costs being displayed with decimals (now all rounded)
Buff/debuff UI now shows up to 15 effects each, increased from 10 each
Pressing F10 while not hovering any skill in the skill tree will save the entire skill tree as an image to the cards directory - should speed up the guide-making process
Time of death on Tombstones is now drawn in a unified format for all players (rather than in the system format as it would produce unsupported characters or too wide outputs)
Updated difficulty descriptions to include some base monster stats and give better guidance on what to pick
"Veteran" difficulty renamed to Heroic
"Heroic" difficulty renamed to Epic
"Mythical" difficulty renamed to "Mythic"
@Items:
Adjusted minimum drop levels for many Legendary items to be closer to the required level for the skills they affect
Added many new items only available via the new Transmutation NPC: 
Mightcap
Elementium Stone
Health Injector Mk2
Mana Injector Mk2
Spell Codexes (many!)
Added other new items:
Champion's Crown (Crafting Material):
This is a special crafting material that is used for some Transmutations, it only drops from Champion enemies
These drop after level 50 on Veteran and higher difficulty
Gravity (True Legendary Amulet):
Doubles all satellites and increases their damage by up to 150%
Rahlence's Resoluton (True Legendary Accessory):
Adds a chance to get random buffs (similar to Shrine buffs) on kills
Changed items/powers:
All:
The Boomer: 
Now causes enemies to explode for up to 10% of Maximum Health in a 3 meter radius on death
Vampire Lord's Cape: 
Now heals the wearer for up to 150% of all mana spent
Jeopardy:
Now stacks with 20% each, down from 40%
The Unbreakable Bond:
Can now be augmented to 90% reduction, up from 80%
Tome of Knowledge:
Is now an accessory
Saboteur's Hood:
Now increases movement speed when breaking breakable objects
Berserker:
Brutal Stompers: 
Now also affects Dragon Leap and Arctic Leap
Bloadsoaked Claw:
Now rolls +Bleed Damage% rather than a Bleed DoT
Templar:
Ayeela's Guard:
Is now a Tome to better fit the build
Renamed to Ayeela's Wisdom
Now always rolls HoH
Warden:
Storm Pendant:
The Nimbus is spawned at rank 1
Stormdweller Hood:
Now reduced mana cost of Storm skills by up to 50%, down from 100% 
Warlock:
Icecrown:
Now causes Frost Spear to also be fired from any active Frost Satellite enchants when cast
@Linux:
Improved gamepad detection (hopefully)
@Localization:
All skills text (names, description etc) is now externally stored and available for translations
Skill keywords etc is now also stored externally
Added support for Simplified Chinese for community translations (change font_type="latin" to font_type="chinese" in the text data file to load up the correct font)
Items and remaining text is coming soon
@Monsters:
Affixes:
Bleeder now damages much less
Added new "Frost Blitz" affix to the affix pool for Champions
All Bleeding effects/DoTs now stop enemy Regeneration affix from working for the duration
Boss:
All:
Boss Health now scales slightly higher with base difficulty, and increasingly so with Anomaly levels
Bosses now clear any active spells when dying, so players don't die after the boss has died
Bosses now get double resistance bonuses from higher diffculties
Captain Moore:
Now announces his axe throw attack, and will pause slightly when doing so
Uniques:
The Botanist:
Slightly lowered damage
Increased cooldown on Fairy Ring skill (poison shrooms)
General:
Reduced damage of some projectile spells when used by monsters, such as Poison Bolts
Monsters can no longer leap, dodge, warp, or evade while frozen, paralyzed, or otherwise stunned
Enemies now start stacking base resistances at Legendary difficulty (lowered from Mythical), and now stacks them much higher
@Shrines:
Shrine locations are now randomized between sessions/resets
Added new "Empowered Shrines", which may randomly spawn. These shrines will always grant two random effects!
Empowered Shrines (nearly) always appear in optional areas
Added new effects:
Cooldown Reduction
Mana Cost Reduction
Physical/Fire/Frost/Lightning/Poison/Holy/Shadow resistance
Removed effect:
Death (this also removes the Achievement for it)
@Skills:
A new experimental change has been added to select skills, where they have had their cooldowns drastically reduced and their mana costs equally drastically increased
Removed some Active Skill slot dependencies from the Templar skill trees because that was just dumb and inconsistent
Mana cost of skills have been overall changed to not grow linearly with your base mana anymore, instead, most skills will require much less on lower levels before they reach their intended per-level cost, so you get a smoother progression and learning curve
@Berserker:
Frost Winds:
Can no longer crit when triggered via Cooling Off, preventing double crits
Molten Veins:
Now has a visual effect
Now breaks breakable objects
@Templar:
Holy Fire:
Since it's now counting as direct damage, meaning triggering passives, the damage has been lowered to compensate
Now deals 35/40/45/50/55% damage, down from 60/70/80/90/100%
Devotion:
Beacon (M):
Both now add to an "Aura Effect" stat visible on the Templar's stat sheet, rather than trying to manually change Auras (also scales and stacks more predictably)
@Warden:
Wild Growth:
No longer reduces cooldown of Leaf Wind / Root Veil, but instead increases their duration
Ice Dash:
Now lasts 1.5 seconds (down from 3) and increases Movement Speed by 50/60/70%, up from 15/20/25
Nimbus:
It's exactly the same at max rank, however each point spend adds a larger bonus now, meaning it starts off much weaker
Damage changed to 101/112/123/134/145%, from 125/130/135/140/145%
Duration changed to 3.4/3.8/4.2/4.6/5 seconds, from 5/5/5/5/5
@Warlock:
Demonic Fury:
No longer triggered by non-damaging skills
Soul Feast:
Now restores 2/3/4% of Health and Mana, down from 4/6/8%
Ritual of Necromancy:
The Use effect now also refresh the duration of existing Skeletons
Curses:
Lowered radius on most low-mid tier curses
Updated all curse skill animations
@World:
Adjusted brightness of some late Act 4 areas to be lower
Slightly adjusted shape of The Chronicon to better fit the NPC's
Added a Trove the the Lost City Temple in Act 4
@Fixes:
Fixed a crash that could occur when attempting to check the most recently played character on Linux
Fixed some skill description typos
Fixed Movement Speed gems not working correctly
Fixed quest "Storms on the Horizon" not having an end objective
Fixed time played on Hardcore Tombstones being written in seconds only
Fixed rare crash related to enemies using projectile spells like Flashfire (such as the boss Pyre in Anomalies)
Fixed issue where some skill procs sometimes would deal too low damage because of an unknown rank (now defaults to rank 1)
Fixed Root Veil visual not fading when the effect fades
Fixed Razor Tips (Warden) carrying Pods even if you didn't have the Seeds passive
Fixed the possibility for other players to be locked out of the Moore fight in co-op
Fixed Korem The Guide not having a marker above his head for handing in the Act 4 finale quest
Fixed "chilled" debuff generally applied by Frozen affix enemies overriding immunities
Fixed some Mastery references to old skill names
Fixed some inconsistensies between Templar Auras and the Devotion passive buff
Fixed Field Training (Templar) being a Buff skill and not an Aura skill
Fixed Overgrowth (Warden) granting some unintended bonus damage
Fixed Blindingt Light (Templar) having over 100% stun chance with Tome of Redemption
Fixed some selection wrapping issues in the inventory when using a controller
Fixed being able to reset areas from the waypoint while in other areas then The Chronicon if using a controller
Fixed waypoints in The Chronicon lighting up and showing names even if you hadn't unlocked them yet
Fixed some bad Puzzle spawns in Rosewood and Deepwood
Fixed some text corruption in various NPC interfaces
Fixed issue where some monster Affix spells would persist between loading screens
Fixed some combinations of monster affix spells potentially causing crashes during cleanups
Fixed Repulse (Templar) not getting better with points spent
Fixed some Act 3 areas spawning Act 1 shrines
Fixed some lights having the flame circles offset incorrectly
Fixed the nametag and overhead health bar overlapping
Fixed speech bubbles overlapping health bar
Fixed issue sometimes preventing you from scrolling all the way down in some menus while using a gamepad
Fixed names not being centered when inspecting Shrines, Chests and other interactable objects
Fixed Freezing Breath visual effect persisting through loading screens and sometimes sessions
Fixed issue with some buff/aura effects resetting their triggers constantly when attacking etc (for example Holy Fire)
Fixed Thundercharged 3 set bonus resetting similarly
Fixed Dragon Leap dealing damage through walls
Fixed several rare inventory scaling related crashes
Fixed being able to enter portals through walls
Fixed issue where the NPC "Vengeful Spirit" wouldn't appear under certain circumstances
Fixed a bad spawn of The Whispering Cavern in The Whistling Canyon
Fixed some items with long item type name such as "Augmented Legendary Spellbook (Offhand)" having overlapping text on item cards
Fixed tooltip delay not working in the skill trees and skill selection popup when using mouse
Fixed Captain Moore moving while throwing his axe
Fixed crash on opening anomaly reward chests under very specific circumstances
Fixed some issues with click to move and the Act 4 final boss
Fixed companions becoming unresponsive and stopping attacks
Fixed some issues with mosnter health calculations and re-etnering areas
Fixed spawned monsters dropping in total health after a player levelup
Fixed waypoints not lighting up in some cases when starting a new Act
Unstable Dimenions portal spawns should now properly clear other Unstable Dimensions (there can only be one)
Avenger (Templar) is no longer triggered automatically with the Thundercharged set if the skill isn't learned