Heroes of the Storm is a free to play... Read All The huge revamp to Heroes of the Storm is out and Blizzard is handing out 20 free heroes to everyone for logging in and selecting the pack you want. I went with the brawlers pack as I've enjoyed playing with Stitches and have wanted to try Muradin Bronzebeard for a bit now. Heroes of the Storm 2.0 added loot chests that unlock for you when you level your character so when you log in if you have any levels unlocked you will get some loot chests! Ultimately the Heroes 2.0 update makes unlocking skins, taunts and mounts a bit more accessible to free to play players and adopts an Overwatch and Hearthstone like loot system.
Heroes of the Storm is a free to play Blizzard brawler that is out now on PC and Mac and if you want to unlock the hero pack you should head over and check it out!
If you are curious to learn more about what Heroes of the Storm is Blizzard has a nice page dedicated to teaching the games core concepts you might be interested in.