Is it like MtG? What's the payment model? Any chance of a quick synopsis for the uneducated?
-H
Think of it like MTG or Yu-Gi-Oh but much more simple.... and its totally free to play. You can buy cards with gold earned from playing the game and the pace at which you earn gold isn't really bad. A casual player can buy a pack of cards every other day or so from my observation. You can buy packs with real money too if you're so inclined but spending real money will only speed up your acquisition of cards it wont get you anything that using gold can't.
Each player starts with 30 hit points and when one player hits 0 hp the game ends. Each player also chooses a Hero to represent them in the match. This Hero is one of 9 classes from World of Warcraft and there are class specific cards for each that are themed around abilities the World of Warcraft classes have. Each Hero also has a unique power that can be used in addition to playing cards. There are also neutral cards that any class can use. Decks are made up of 30 cards. No more and no less. Each player starts with 1 mana, the resource you use to play cards, and gains an additional mana each turn to a max of 10 mana per round to spend.
There are creature cards with an attack value and an hp value. Unlike MTG, creatures CANNOT be used to block other creatures specifically.Some creatures, however, have a property called Taunt. If you have a creature with taunt under your control your opponent will not be able to attack you directly and must attack the creature with taunt or forgo attacking that turn. Taunt does not prevent spells from being used directly against your opponent though.
There are spell cards with a variety of functions. Some do direct damage to either minions, enemy Heroes (players), or both. Others allow for card draw, buffs, debuffs, removal of enemy minions, etc. A subset of spell cards called Secrets also exists. Only some classes have secrets currently (Mages, Paladins, & Hunters). Secrets are sort of like face down Trap cards that hang waiting to be triggered.
A category of cards that doesn't really fit either creature or spell are Weapon cards. Weapon cards can be equipped by your Hero allowing them to attack directly as if they were a creature. Only some classes have weapon cards currently and some have a wider array than others (Rogues, Warriors, Paladins, Hunters, Shaman), but the Warrior seems to have the biggest selection to choose from.
Like most CCG's there is card rarity with a Basic set that everyone starts with (which includes some very good cards btw) and then cards from packs that range in rarity from Common, to Rare, to Epic, to Legendary. Players can have up to 2 copies of any specific card except Legendary cards in their decks. Legendary cards are restricted to 1 copy per deck (but you can have multiple different Legendary cards in a deck). While some Legendary cards are game changing its quite easy to do well (even against players using Legendaries) with a deck made of mostly Rares and Commons.
I hope I covered the basics there! If you have any specific questions feel free to ask and I'll answer as best I can!