Sure. Here’s every single nerf from every single patch from patch 1.1 to patch 1.12. They’re including all of them, since 1.12 included all of them, as they all happened mostly in previous patches.
 
Anyways. Here we go: I’ve scanned all the Classic patches from 1.1 to 1.12, and compiled all the nerfs and major changes made to instance difficulty and overall gameplay and itemisation. I left out all the changes made to Classes, talents trees, professions and in-depth item changes.
 
Patch 1.1 and 1.2 - Didn’t bring major changes in terms of gameplay or progression to the game, only some minor class tweaks. Maraudon added to the game.
 
Patch 1.3
 
This were changes to raid/dungeons difficulties started to happen.
 
New dungeon Dire Maul – 5 man cap
 
New world bosses - Azuregos, and Lord Kazzak
 
MC teleport quest - Attunement to the Core
 
New dungeons player caps – All dungeons and raids were previously 40man cap, with the new patch they’re now the following, Ony/MC 40man, UBRS/LBRS 15man, Diremaul 5 man, every other dungeon 10man. Several dungeons will be re-examined for balancing in light of this change.
 
Nerfs to dungeons and raids (and some loot changes) –
 
    Lengthened the respawn time of many of the creatures in Ragefire Chasm, Gnomeregan, Uldaman, Razorfen Downs, Scholomance, and Stratholme.
 
Onyxia
 
    Onyxia’s fireballs will no longer result in a confuse effect (Engulfing Flames). The impact damage of these fireballs has been slightly increased to compensate for the loss of the damage over time.
    Increased the delay before Onyxia will try to tail sweep.
 
Stratholme
 
    Baroness Anastasi in Stratholme will now leave the possessed target when the target is below 50% health, instead of 30%. She will also cast Possession slightly less often.
    Roaming Gargoyles will be set to a 30-minute respawn.
    Roaming Shades set to 15-30 minute respawn (previously 5-15).
    Patchwork Horrors set to 15-30 minute respawn (previously 6-10).
    Overall respawn in the entire dungeon made longer.
    Crimson Conjurers will no longer roam in pairs.
    Crimson Conjurers can now only have a max of two "pets" at one time.
 
Scholomance
 
    Lengthened the overall respawn of the dungeon.
    Risen Aberration health and damage reduced.
    Reduced the duration of Dark Plague from three minutes to 90 seconds.
    The creature spell, Call of the Grave, has had its damage reduced by half.
 
Blackrock Spire
 
    Spire Spiders now only summon four Spire Spiderlings instead of five.
    Health and damage on these Spire Spiderlings has been reduced.
    Crystallize has been reduced from eight seconds to six seconds.
 
Maraudon
 
    Noxxion encounter made easier for groups lacking area of effect damage.
    Zul’Farrak
    Dead Hero will now always drop an uncommon random item.
    Witch Doctor Zum’rah’s loot table was improved.
    Toned down the Zigguraut event.
    Toned down the Antu’sul event.
    Scarabs will no longer flee when at low health.
 
Patch 1.4
 
After patch 1.3 changed the player caps, many dungeons were nerfed and their loot tables received major buffs making Raids such as Ony and MC easier due to better gear stats.
 
Major change to the 5 seconds rule and how healer play in general – “Mana regeneration is now disrupted when a spell has completed casting rather than at the start of casting. It will resume normally five seconds after the last spell cast. This change increases the total time spent regenerating mana and therefore increases the total contribution from Spirit for mana-based classes.” This allowed a playstyle of pre-casting heals and interrupting them when the tank avoids dmg, by blocking parrying or dodging, making it much easier to save mana while keeping the tank always full HP.
 
Nerfs to dungeons and raids –
 
    Bael’Gar, Lord Incendius, and Golem Lord Argelmach are now lower level than previously.
    The Baroness Anastari encounter has been changed. Players who become unpossessed will now have full health, and after the Baroness unpossesses a player there will be a much longer cooldown before she can cast possess again.
    Lava Surgers no longer respawn once you kill Garr.
    Ragnaros now stays up 2 hours rather than 1 after being summoned.
    The Golemagg and Shazzrah encounters in the Molten Core has undergone some changes. (nothing specified in the patch notes, but probably nerds aswell)
 
Major itemisation buffs to all high level dungeons (many blue rare items were added to the game making the content a lot more trivial) –
 
Scholomance Itemization
 
    20 new Rare items have been added to Scholomance.
    Several Uncommon items have been upgraded to Rare quality.
    Rattlegore, Jandice Barov, and Lord Alexei Barov will now always drop at least one Rare item.
    Ras Frostwhisper will always drop at least two Rare items.
 
Stratholme Itemization
 
    26 new Rare items have been added to Stratholme.
    Several Uncommon items have been upgraded to Rare quality.
    Archivist Galford, Baroness Anastasi, Nerub’enkan, and Maleki the Pallid will now always drop at least one Rare item.
 
Raid Itemization
 
    Onyxia, Azuregos, Lord Kazzak, and all Molten Core boss creatures have all received some new items on their loot tables.
    Onyxia will once again drop two upper tier class set helms.
    Most of the non-class set items that dropped from Molten Core and Onyxia have had their effective levels increased, resulting in higher DPS weapons, and/or better stats and effects.
    Players who defeat the Majordomo Executus encounter will now be rewarded with new epic items. This reward will only be granted the first time the encounter is defeated during the 6 day lifespan of a Molten Core instance.
    The loot tables for some of the Molten Core bosses have been improved so they drop an additional epic item per kill.
    World bosses such as Onyxia, Azuregos, and Lord Kazzak will no longer drop random blue items of a level lower than 50 (buff because it will drop high level items instead).
    Prior to this patch, Molten Core boss creatures could drop items from one of two different tiered sets for every character class. The loot tables have been changed so Molten Core bosses will now only drop items from the lower tier class sets. However, some of the items from those sets were not previously dropping in Molten Core. These missing class set items will now drop in Molten Core, allowing players to complete their lower tier class sets. The higher tier class set pieces that once dropped in Molten Core will be found once again in Blackwing Lair, the next raiding zone scheduled for release in a future patch (this only happened in US servers, because EU was release later and didn’t have acces to tier 2 sets on MC).
    Future patches will include even more item rewards for these raid encounters, as well as improvements to the statistics, effects, and set bonuses for both tiers of the raid armor sets.
 
Patch 1.5
 
Battlegrounds were introduced and Ragnaros had a minor nerf, new items.
 
Molten Core
 
    Lava eruptions (lava splash) only occur while Ragnaros is in combat, but occur less frequently, do less damage, and the damage they inflict is now resistible.
    Additional new raid items have been added to the treasure lists for Azuregos, Lord Kazzak, and bosses in Molten Core.
 
Patch 1.6
 
BWL is introduced
 
1.6.1 patch - The timer for Vaelastrasz the Corrupt is now more persistent. You can no longer reset the one-hour time limit for beating him by leaving the instance. Also, Vaelastrasz the Corrupt will not respawn for 12 hours if he has not been beaten when the timer expires.
 
Darkmoon cards introduced.
 
Raids and dungeons
 
    Several spawns removed from Scholomance.
    Several spawns removed from Stratholme. Also, you will now be able to make additional attempts at Ramstein and/or Baron Rivendare should your initial attempt fail.
    The trapped chests in Stratholme will now show up for [Detect Traps] and can be disarmed. In addition, the number of creatures that come out of the trapped chests has been reduced.
    The loot tables in Molten Core have been revised slightly.
    The chance for an Epic quest item dropping from the Majordomo’s chest has been increased to 100%.
 
Patch 1.7
 
ZG introduced
 
AV introduced
 
General
 
    Debuff limit increase to 16 (previously 8)
    Switching weapons in combat triggers a 1 second global cooldown for all abilities for rogues and a 1.5 second global cooldown for everyone else.
    When you swap weapons in combat, you start your swing again, instead of continuing your last swing
 
Patch 1.8
 
Dragons of Nightmare world boss introduced.
 
Dungeons and Raids –
 
Zul’Gurub
 
    Reduced the damage of the Mad Servant’s fireball
    Reduced the number of Mad Voidwalkers that are summoned from the death of a Mad Servant from three to two.
    Slowed the rate at which High Priestess Arlokk’s panthers spawn
 
Blackwing Lair
 
    There is no longer a one-hour time restriction on the Vaelastraz the Corrupt encounter in Blackwing Lair.
 
Patch 1.9
 
AQ Raids introduced.
 
Changes to Raid Calendar System - The raid-lockout system has undergone a significant change. The new system will have all instances reset at a certain server time, regardless of when you were actually saved to the instance. The reset schedule is as follows:
 
    Molten Core: Every 7 Days, resetting during weekly maintenance.
    Blackwing Lair: Every 7 Days, resetting during weekly maintenance
    Onyxia: Every 5 Days
    Zul’Gurub: Every 3 Days
    Temple of Ahn’Qiraj (40-man): Every 7 Days, resetting during weekly maintenance
    Ruins of Ahn’Qiraj (20-man): Every 3 Days
 
Dungeons and Raids (1.9.3) –
 
Zul’Gurub
 
    A small number of spawns have been removed from Zul’Gurub to allow for a slightly faster clearing time.
    Increased cooldown on Poison Bolt Volley of High Priestess Mar’li.
    Reduced the melee damage of High Priestess Mar’li.
    Reduced the overall damage of High Priest Thekal.
    Slowed the rate at which the panthers spawn during the High Priestess Arlokk fight.
    Reduced the duration of Lethon’s Draw Spirit from 7 seconds to 5 seconds.
 
Hakkar
 
    Melee damage reduced.
    Cause Insanity will no longer remove all threat gained.
    Reduced the damage dealt by Poisonous Blood Siphon.
    Increased cooldown on Blood Siphon.
    No longer has the Slow ability.
    Corrupted Blood now deals direct damage with a following damage over time effect and no longer spreads to others in the raid.
 
Patch 1.10
 
Weather Effects!
 
High-Level Armor Sets introduced (tier 0.5)
 
High-Level Instance Changes - Along with the new Armor Sets, the high-level 5-10 man dungeons have received some changes regarding loot. Many items have been improved in quality and use. In addition, several epic items, have had their drop rates significantly increased. In order to preserve the challenge of these dungeons, they have had their instance caps lowered. Stratholme, Scholomance, and Blackrock Depths now allow a maximum of 5 players inside, and Blackrock Spire allows a maximum of 10.
 
Itemisation buffs –
 
    Relics have been introduced to the game. These are class specific items for Druids, Paladins, and Shaman which can be equipped in the ranged slot. Currently there are a handful for each class which can be found scattered throughout Blackrock Depths, Blackrock Spire, Dire Maul, Scholomance, Stratholme, and The Temple of Ahn’Qiraj. We hope that you enjoy the first round of available relics and we will continue to add more in future patches.
    Many items in Blackrock Depths, Stratholme, Scholomance, and Blackrock Spire have been re-evaluated and adjusted to make them more appealing. In addition several new items have been added to all of these instances.
    The following item sets have had their set bonuses adjusted/increased: Valor, Magister’s, Lightforge, Shadowcraft, Dreadmist, Devout, Wildheart, Beaststalker, and Elements.
    The locations of some of the waist, wrist, and hand slot pieces of the dungeon armor sets have been moved from their old creatures, including the [Lightforge Gauntlets] and the [Magister’s Boots]. Additional creature types can now drop many of the previously difficult to obtain armor pieces.
 
Raids & Dungeons –
 
Ruins of Ahn’Qiraj
 
    Ayamiss the Hunter now flies down from the air much earlier.
    The Plague effect from Anubisath Defenders and Anubisath Sentinel’s is no longer amplified by +damage gear.
    Removed the stacking acid from the Flesh Tentacles in the C’thun encounter.
    Digestive Acid now increases its effect over time during the C’thun encounter.
    Lowered the amount of knockback dealt by Giant Tentacles.
    Tentacles should no longer spawn on players who have just been knocked back by a previous tentacle.
 
Blackrock Spire
 
    Some monsters were removed to reduce the time it takes to run the dungeon.
    Mother’s Milk off Mother Smolderweb will now only affect players.
    Spire Spiderlings now have fewer hitpoints.
 
Patch 1.11
 
Naxxramas introduced
 
Dungeons and Raids –
 
Zul’Gurub
 
    Class specific armor quests given by the Zandalarian trolls of Yojamba Isle no longer require Bijous or coins for completion. Armor quests now only require a Primal Hakkari piece and appropriate faction with Zandalar.
    Class specific enchantments given by Zanza the Restless no longer require Arcanum (Librams) from Dire Maul. The requirements have been changed to items found within Zul’Gurub. Speak with Zanza the Restless for more information.
    The various clan speakers (Bloodscalp Speaker, Sandfury Speaker, etc) have had their hit points reduced considerably.
    Zandalarian Armor Replacement - Due to the changes made to the armor rewards from the Paragons of Power quests, the trolls of Yojamba Isle will now offer to replace pieces of armor that have been lost or deleted.
    After careful consideration we have decided to add an additional loot table to the High Priests of Zul’Gurub. Players should now see two items in addition to the tokens when slaying these bosses.
    When Hakkar gains the Berserk effect, Hakkar will now emote that he is berserk instead of emoting that he is enraged.
 
Ruins of Ahn’Qiraj
 
    Ossirian the Unscarred - There is a new crystal that will be visible before the encounter begins. Players can use this crystal just like any other crystal in the encounter, but it cannot come back up during the encounter.
    Ruins of Ahn’Qiraj Class Set Reward Replacement - Due to the changes made to the rewards from the Ruins of Ahn’Qiraj class set quests, players can obtain replacements for lost or deleted quest rewards from Warden Haro, Keyl Swiftclaw, and Windcaller Yessendra in Cenarion Hold.
    The hitpoints of every creature in the General Rajaxx encounter has been lowered.
    Damage of General Rajaxx has been lowered.
 
Patch 1.12
 
Raids and Dungeons –
 
Uldaman
 
    Reduced the number of Shadowforge Ambushers that attack after looting the quest chest.
    Shadowforge Ambushers are no longer elite.
    The respawn of the Stone Stewards has been changed to 2 hours (from 30 minutes).
 
Zul’Farrak
 
    The respawn of the 2 Troll/1 Basilisk patrollers should now be 2 hours.
    Reduced the damage dealt by the Sul’lithuz Abomination and Sul’lithuz Sandcrawler.
    Zul’Farrak Dead Heroes are no longer elites.
    Theka the Martyr will now only remain immune to physical damage for 30 seconds before reverting to normal.
    Antu’sul’s Sul’lithuz Broodlings now only hatch 4 at a time and are significantly weaker.
    Witch Doctor Zum’rah will no longer call as many Zul’Farrak Zombies to his aid when aggroed.
    Antu’sul’s Warden no longer attempts to knock adventurers into Antu’sul’s lair.
    Sandfury Cretins who engage the party during the pyramid event are no longer able to cast shadow bolt.