"The flow of time is always cruel... its speed seems different for each person, but no one can change it... A thing that does not change with time is a memory of younger days..."
Hunter: Deathstalker Rexxar,Dire Frenzy, Toxic Arrow - First card is my favourite DK since the beginning of his existence in Hearthstone, second and third card are niche, generally useful and have a deck slot in nearly all my Reno Hunter variations.
Mage: Frost Lich Jaina - This card is a sole reason why I started experimenting with Reno Mage archetype and Mage in general.
Paladin:Prismatic Lens, Uther of the Ebon Blade - First card requires creative deckbuilding to pull off extraordinary combos, second card has an incredible flavor that I really love.
Priest: Archbishop Benedictus - Playing with your opponents' resources is one of the most funny thing to do in Hearthstone. Archbishop creates and wins many ridiculous games.
Rogue: Shadowcaster, Sonya Shadowdancer, Tess Greymane, Valeera the Hollow - I personally love the "throw everything on board" type of cards and so is Tess. The rest of cards is unique design (first and second card) combined with incredible value (the last card).
Warrior: Dr. Boom, Mad Genius - This card is a sole reason why I started experimenting with Control Warrior archetype and Warrior in general.
Neutral: Azalina Soulthief, Coldlight Oracle, N'Zoth, the Corruptor - Oracle is my favourite card craw, which I use in all kind of decks from Aggro to Control because he is efficient for his mana cost and he can mill your opponent's important cards. Azalina reads your opponent's hand, gives you valuable resources and a ton of fun. N'Zoth is my favourite (next to the fatigue) win condition for control decks.
Tirion Fordring
Because well, he is Tirion Fordring...
"The flow of time is always cruel... its speed seems different for each person, but no one can change it... A thing that does not change with time is a memory of younger days..."
I’ve loved avianna since tgt she was the first legend I crafted and playing decks with her I became a golden Druid really quickly
King Togwaggle
Or any card that make your opponent say "fuck you"
Well, it will be a long list...
Honorable mentions: Baku the Mooneater, Chameleos, Genn Greymane, Reno Jackson, Yogg-Saron, Hope's End.