Note: there was over 400 things that the TKoK team has found and I corrected for this 3.1.1 patch. No way I am going to list them all, here are just the major things.

Generic Bug Fixes
Camp Fire no longer shares a cooldown with wards
Terrain changed around VJ's air and earth elementals to prevent luring them out without starting the fight.
Found issue with VJ air elemental code that could explain the fatal reported and some other random problems. Fixed it.
Using Save & Quit, Dying on HC, and Leaving the game now all share one common 'cleanup' function for undoing the hero setups and removing quest items and so on. This also fixes the issue of leaving/dying with buffs on and causing an issue (HC/Save & Quit)
Fixed an issue with the logic behind Time Strike's multiple hits and unit death events
Changed the way Muarki's add's death events function (fixes an exploit also is a game play improvement)
Karnos' visual attachment for him becoming Empowered for hardmode now properly is removed on reset or death
Fixed a logical flaw in all boss death cleanup functions that may cause some errors over long games (with multiple boss kills per game)
Removed the "ID==0 on 'unit name'" debug message. You would really only see this message in the Frost Side of the temple, not a bug, just letting me know a unit died that wasn't in the indexing system, which in this case was just a hidden dummy caster with a timed life. No cause for alarm people, move along now.
Corrected an issue with spawn events that didn't properly init a much needed variable for some damage event conditions. The most noticeable bug fixed was Naztar's instant death.
Fixed an issue with HC deaths that caused a game to goto single player mode.
Corrected a few unit death cleanup events that could result in a Double Free of Aggro type
Altered the AggroBar text tag system to use 1 variable and client side edits. This corrects the 'dead threat bar' issue
Fixed a few issues with Muarki and altered the way the adds 'die' in phase1. Helps prevent some pathing exploits, revival code, death event issues and some other things I won't go into
Fixed an issue with Tank Toss with Muarki that causes the fight to reset if the tank is the only player left in the box at the moment.
Fresh level 1 characters now properly get their first talent point again at level 1. Don't worry, if you save and reload into a fresh game, TKoK detects you are missing a talent point and rewards it back to you.
Fixed a few issues with boss cleanups, dummy units, and other things that would cause a Double Free or an ID==0 bug on several fights
Revamp of every Ability tooltip in the game (Thank you Hally for taking the time to do this) and edits to a lot of Talent Tooltips to fix errors, mis-data, and other things of the sort

Cleric
Inner Power is now an AoE buff instead of single target. Cooldown and mana cost adjusted

Pyro
Burning Desire is now an AoE buff instead of single target. Cooldown and mana cost adjusted
Adjusted the offset of Dragons Breath to be able to hit point blank targets better
Adjusted meteors explosive timer to be more visually correct with the graphic of it landing

Hydro
Fixed an issue that can cause the Hydro's Nova to sometimes do 1 damage to surrounding enemies, but not always.
Hydro's Tsunami now always leave a 'frost' debuff even if you do not have it improved. The improved still adds the slow as usual.
Adjusted the offset of Purify to be able to hit point blank targets better

Druid
Fixed an issue that caused Starfall to do what seemed to be random damage. Starfall will now do its true damage all the time
Fixed issues with the multiboard and the druid along with the broken icons.
Changed the shapeshift cooldown to the proper shapeshift icon
Fixed a the respec issues with the Druid and his auras
Fixed the bug with Serenity aura's magic resist along with the bear form and abilities magic resist. They will now add the proper values
Fixed bug with mending touch and rejuvenation. And you can now get a double heal with mending if they have rejuv and lesser rejuv both.
Fixed bug with emp barkskin + peaceful mind or mending touch
Fixed tooltips for ignition, bark skin, mending touch and arcanic missile
Fixed bug with moon fire buff being instantly confused by the moonfire's own damage
Fixed issue with bear block
Fixed an issue with Shape shifting during several abilities that last over a period of time
If you cast Hibernate while you have enrage on, enrage recasts itself the moment Hibernate ends
Adjusted the offset of Fury Swipes to be able to hit point blank targets better

Vjaier Related:
The Fire Elemental can no longer knock people into the side walls or barrier and get them stuck in certain spots
The pulse counter no longer counts pulses mid-air when Vjaier dies (Can screw up a VX mode since it technically cannot hit Vjaier if he dies mid flight)
It is possible in some situations that a Tornado spawned by Vjaier will not do a 'Pull In' at the end of its path. Won't go into details, but I found the issue and corrected it. Doesn't happen with every tornado, only under certain circumstances.
Vjaier now has a proper stats display when the fight ends letting you know how many pulse there were, how many hit Vjaier, and the %. (90% or more required for VX)

Crueltis Related:
Larthils Spears now drop from a players inventory if they die during the fight
Fixed an issue that would cause Ithan and Larthil's threat to not reset when you reset the waves
If during Crueltis' opening speech everybody exits the area and does not re-enter before the speech finishes, Crueltis will reset at the last chat message. This is correct, however, Crueltis will not change from a friendly mob into an enemy mob if reset in this manor. Thus when the fight is started a 2nd time, the opening speech does not trigger and he remains owned by Player 10 (Citizens). To avoid this for now, if you choose to reset the fight as he is spawning to re-group, heal, or whatever. Wait until he actually begins the fight before running out to reset.
Fixed an exploit with Crueltis' adds (spawned centaurs)
Fixed issue that caused Crueltis not to do his Dark Beams ability sub 20% hp
The Light Beams for protection from Crueltis now last 3s after Darkness happens. Also to clarify something: A Light beam protects against ALL forms of Crueltis spell damage. This includes Crack The Ground (the moving earthquakes), Power Wave (the ability he uses on the chief), etc.
Crueltis Adds stop using abilities once darkness begins to fall
General Crueltis adjustments to his damage output, VX mode, several bug fixes and other adjustments with his buffs. VX mode buffs nerfed a bit, healing Cruel receives remains the same
Fixed a few different exploits regarding darkness and the adds
Fixed an issue that could sometimes crash Crueltis during phase3, the last stand

Generic Balance Edits:
Cruel Nerfed
Karav and VJ nerfed a bit too
PS base attack speed is 1.7 (from 2). Barb, SB and ranger now 2.2 (from 2.5, 2, 2.25 respectively)
PS spell damage coefs increased (especially remorseless) and some cool downs lowered, but some mana costs increased
Barb increased spell damage part of Berserker Rage and bladestorm. also buffed battle lust.
Damage increased on some PS spells, especially Remorseless Strikes
Fireform adjusted (in between 3.0.4 and 3.1.0 versions, plus less scaling in future)
Meteor cool down increased
Paladin armor/dodge talent nerfed
Drain spirit damage gain per tick buffed
Arcanic disruption debuff duration to 4s (from 2)
Druid adjusted
Cruel base hp lowered 44k to 42k and his level is fixed (should be 29), moonbeams now start at 25% life (from 15%), and lowered the hail of arrows
damage from his summoned centaur from 45 to 40.
Randomized XP and Gold rewards (+/- 20%) and fixed rounding issues with gold/xp gain items. Randomizing avoids breakpoints with certain xp/gold gain percent bonuses against certain enemies. Quest rewards are not randomized.
wisdom sp is .7 from .75, ene sp is .5 from .4
Enemies level 28+ on normal now count as one level lower for XP
Halved the mana bonus from Battle Orders but increased damage from counter attack