Basic

Mind Control: Change mana cost from 10 to 9
Bloodlust: Change mana cost from 5 to 4, minions cannot attack face this turn
Swipe: Only affects minions
Charge: Change mana cost from 3 to 2, Give a minion +2 attack and it can pass through taunt this turn only instead of getting charge
Drain Life: Change mana cost from 3 to 2
Savage Roar: Give your friendly characters +2 attack this turn only against minions
Backstab: Change mana cost from 0 to 1, deal 3 damage to instead of 2
Hunter's mark: Change mana cost from 0 to 1
Innervate: Change mana cost from 0 to 1, Refill 3 empty mana crystals or gain 2 mana crystals this turn only.
Moonfire: Change mana cost from 0 to 1, deals 1 damage to a minion twice.
Sacrificial Pact: Change mana cost from 0 to 1
Totemic Might: Change mana cost from 0 to 1, give +3 health for your totems

Classic:

Mountain Giant: cost 1 less for each minion in your hand
Alexstraza: Set health to 20
King Krush: Change mana cost from 9 to 8
Lord Jaraxxus: Change mana cost from 9 to 10
Tirion Fordring: Change mana cost from 8 to 10
Ancient of Lore: Draw only 1 card instead of 2
Prophet Velen: New text: Battlecry: Your hero power heals or deals damage twice the amount that it would normally.
Holy Fire: Change mana cost from 6 to 5
Faceless Manipulator: Choose a minion and become a copy of it at the end of your turn.
Mass dispel: Silence all enemy minions then deal 1 damage to them.
Mind Games: Change mana cost from 4 to 5, Put a random minion from your opponents deck into the battlefield
Master of disguise: Gain stealth at the end of your turn
Divine Favor: Draw as many cards as many you drew last turn.
Shadowform: Change mana cost from 3 to 2.
Big Game Hunter: Change mana cost from 3 to 5.
Blade flurry: Doesnt deal damage to face.
Equality: Change mana cost from 2 to 3.
Knife Juggler: Juggle can hit friendly targets too
Lightwell: restores health at the end of the turn
Sorcerer's apprentice: after reduction, Spells cannot cost 0 mana
Power Overwhelming: There's an 50% chance that your minion will hit another enemy target instead. (per stack of PO)
Abusive Sergeant: Gives only +1 attack.
Leper Gnome: Deal 1 damage only with deathrattle
Circle of Healing: Change mana cost from 0 to 1
Preparation: Change mana cost from 0 to 1
Shadowstep: Change mana cost from 0 to 1


Curse of Naxxramas:

Void Caller: Change mana cost from 4 to 5
Stoneskin Gargoyle: Change attack from 1 to 2
Mad Scientist: Change mana cost from 2 to 3
Nerubian egg: Deathrattle: summon 4/3

Goblins vs. Gnomes:

Mal'Ganis: Change mana cost from 9 to 10
Dr. Boom: Boom bots deathrattle can hit friendly characters too. (this is how goblin engineering works tho)
Recycle: Change mana cost from 6 to 5
Piloted Shredder: Change health from 3 to 2
Coghammer: Change mana cost from 3 to 4
Muster for Battle: Equip the weapon at the end of your turn.
Call pet: Cannot cost 0 mana
unstable Portal: Cannot cost 0 mana
Mechwarper: Change cost from 2 to 3 mana.



Blackrock Mountains:

Emperor Thaurissan: Change stat line from 5/5 to 6/6, Mana cost reduction applied at the start of your turns.
Flamewaker: Change mana cost from 3 to 4, Change health from 4 to 5


The Grand Tournament:

Mysterious Challenger: Change cost from 6 to 7 mana.
Spawn of Shadows: Inspire: Deal 1 damage to other minions
Poisoned Dagger: 4 durability instead of 3


League of Explorers:

Anyfin Can Happen: Change mana cost from 10 to 9, Summon the murlocs at the end of your turn
Excavated Evil: Change mana cost from 5 to 4
Keeper of Uldaman: Change mana cost from 4 to 5, change attack from 3 to 4