The tutorial is the in-built step by step guide to teach new players the game. Through it, you learn mechanics and gain cards. The encounters are scripted so that, unlike the real game, your opponent does not get random cards. After having completed the tutorial, you will have gained a certain amount of cards and a rudimentary understanding of the game. Your hero will be Jaina Proudmoore. After having completed the tutorial you will get to choose a hero by yourself.
Your first encounter is against Hogger, a non-playable hero. He does not have as much Health as normal heroes and he does not belong to any class. He will mostly play minions against you (see his page for a detailed overview). The game will tell you what to do and he is very easy to beat. After having beat him, you will be awarded Arcane Intellect x2.
The second encounter is against another non-playable hero, Millhouse Manastorm. He belongs to the Mage class and he will play a great deal of spells (see his page for a detailed overview). He often targets your minions and should be easy to kill off, thanks to him targeting your minions instead of you. After having beat him, you will be awarded Novice Engineer x2.
The third encounter is against Lorewalker Cho, who is also a non-playable hero. He does not belong to any class and he does not have any hero powers. He will mostly play minions along with a few spells, but his cards are of low value and he does not get the option of drawing additional cards, unlike you. Thus, with time, you will be able to use your mana more efficiently and will be able to win without much problems. Your reward for beating him is Wolfrider x2.
The fourth encounter is against King Mukla, again a non-playable hero who does not belong to any class. He starts off with a couple of crazy cards, then a couple of strong ones and then a really strong one. However, you should be able to kill him off, disregarding his minions. If you like to focus on his minions, he will resort to Barrel Tosses for the rest of the game, hurting you 2 Health per round, but giving you ample opportunity to hurt him back with your minions. The reward for defeating him is Polymorph x2
The fifth encounter is against Hemet Nesingwary, a hero belonging to the Hunter class. He does, however, differ from the playable hero, Rexxar in that he does not have the same amount of Health. He will play a lot of minions but if you take those out, you should be pretty safe and able to get in enough damage to eventually kill him off. The reward for defeating him is Reckless Rocketeer x2.
The last and final encounter is against Illidan Stormrage, a Hunter class hero who, unlike the others you have faced, is quite overpowered with a hero power that lets him spawn two minions every time he uses it. Despite a worrying start however, you will get "lucky" with the cards you get, being able to eliminate the threats as they pop up and eventually, you will take him down. The reward for defeating him is Arcane Missiles x2.