Sprint Cost 7 mana sorry about that.

Malygos’s Intellect: Cost 3 mana, “Draw 4 cards.”
Sprint: Cost 3 mana, “Draw 4 cards.”
So it is basically Malygos’s Intellect= 3 mana sprint.

It seems like upgraded mage spells come from basic set, also it looks like if you see a number in a text +2 to it, if adding +2 meaningless lets play around to mana cost which could be “1”. Therefore my predictions for the remaining cards are:

Arcane Explosion: Cost: 2 mana, Text: Deal “3” damage to all enemy minions.
Arcane Missiles: Cost: 1 mana, Text: Deal “5” damage randomly split among enemy characters.
Flamestrike: Cost 7 mana, Text: Deal “6” damage to all enemy minions.
Frost Nova: Cost “1” mana, Text: Freeze all enemy minions.
Frostbolt: Cost 2 mana, Text: Deal 5 damage to a character and Freeze it.
Mirror Image: Cost 1 mana, Text: Summon four 0/2 minions with Taunt.

What do you think?