This deck could easily be called an Elemental Mage due to its significant number of Elemental creatures. But actually, it has so many other things going on that it is not purely an Elemental archetype.
The current meta requires a bit more flexibility, especially when it comes to dealing with control decks that use many spells. That’s why Counterspell is essential to this deck, as well as the new Frozen Clone secret that adds two copies of the enemy minion to your deck.
Volcanic Potion and Polymorph are just as necessary for dealing with either a horde of small minions or removing one big threat from the board. And when the path is clear, you can start churning out your Elementals for eventual victory.