Colourful Casting Card Design Competition

I tried my best

Some new Discard support for Zoo outside of Nightshade Matron. Basically gives a free casting of Fiendish Circle, which also enables Ritual of Doom. If Hand of Gul'dan is a Fel spell, it might be strong, but I think it's fine when compared to the immediate effect of Matron.

His test subjects report a fuzzy feeling and a strange desire to wear large hats.

'Well, I can't imagine this will ever need to be nerfed.'

Attended to and graduated from every single class in Scholomance. Who needs a Time-Turner when you have COFFEE? 

Maybe he runs away easily, but he does it with a blast!

Yes, that stacks!

"He brings the Light...and the pain."

Jan'alai, the Dragonhawk summons Ragnaros the Firelord, so why not a card that can summon Ragnaros, Lightlord?

"Need a fire?"

As of right now, we have just 2 Frost spells.

The idea is if the right synergy is applied, the frozen effect can obliterate large boards with just a couple of cheap spells.

Fun note: Ice Barrier would deal 3 damage to your own face. Totally intended to screw Secret Mage.

Holy Spellburst works identically to regular Spellburst except that it only triggers if the spell was from the Holy Spell School. The Holy spells can be found in Paladin and Priest making this a nice early/mid-game removal and body for both classes.

The trifling gnome returns! Just don't let him summon a doomguard...

Char, chill or sparkle? Kirin Tor Tricaster's source of power poses a deckbuilding challenge. Balance the elements carefully, and you will be rewarded with buffed boardclears and a strong burn-style finisher. However, the power quickly fizzles out if you can't continue the chain!

I love the Wardens in WoW. Maiev got her card so figured throw in Cordana. A Warden corrupted by the alternate Gul'dan on Draenor and assisted him in breaking into the Warden's Vault setting free many dangerous prisoners. The final confrontation with her involved finding stealthy minions with light on a small platform while dodging glaives and shadow spirits. 

Summoning a bunch of copies is a nod to that fight. Easy to avoid but dangerous if ignored. Demon Hunters and Warlocks have cheap Fel spells that can make her a decent threat that multiplies quickly if left unchecked.

Tyrande hit her emo phase a few centuries later than most elves.

Filled with the dark power of the wrath of the moon goddess Elune,  Tyrande has been on a rage-fueled rampage for the past couple years in WoW in retaliation for Sylvanas Windrunner burning down her home. What once was a source of light has turned to shadow as the phases of the moon. 

Ignite your fire spells - making them much better at kiling all kinds of minions!

Ignite your Combustion or Rolling Fireball to destroy hordes of minions.

Ignite your Forgotten Torch to add more fire spells to your deck!

Ignite your Molten Reflection to make more Imprisoned Phoenix and destroy your enemy!

Dryad of Duskwood is a versatile card for Druid able to draw some cards with its first choice, or open up some possible combo plays with the second choice synergizing with Nature spells.

The idea of combining opposite spell schools in a single card seemed quite fun and the result feels very flavorful, especially for a class like Priest.
Gameplay wise, this could be a very decent card in the returning Shadow Priest archetype.

"Fire and Frost are both so intense, put 'em together it just makes sense."  While most mages will choose between Fire decks and Frost decks, the Dual Specialist asks why not both? While he's a good fit in either Fire or Frost archetypes, you can combine the two and unlock his full potential.

Rush
Battlecry: Gain +1/+1 for each Fire spell you played last turn.

There's a reason she only uses nature spells - flaming treants never go well.