First order of business: this is not a good deck. Second order of business: under no circumstance should you craft this deck.
Now that that's taken care of, GB Spellflux Cannon is a combo deck that relies on three major cards; Spellflux Cauldron, Allfather's Horn and Academy Recruit. The idea is that once you've equipped Spellflux, you can play recruit and horn in the same turn (for a reasonable amount of 9 mana), cast a few more spells and win the game from there. Usually, you'll kill your opponent with a well timed horn and whatever weenies you have on board.
The deck normally works like this: you maintain yourself alive by playing some efficient blocking dorks such as ensnaring serpent, einherjar thane and Born-again. Once you reach the early midgame, you start using spells to protect yourself and keep a few dorks alive or cast just good cards like Magnus, Bragi or Bela. Once you reach 6 mana, you can start having some fun casting things that draw you cards and playing powerful individual cards like Murmur and Zira, or get some value from the Recursionist (NEVER play recursionist unless you have a follow up spell that turn or you're up against an extreme aggro deck and you really need to block). Once you make an opening, you grab your dorks, your spellflux (you can play it during a turn you don't have much to do, it's rare that the opponent will be able to actually blow it up) and you horn your opponent to death. An important thing to note before moving on: you'll usually want to have 2 blue and 4 green by six or 3 and 3. But remember that green is your heaviest color and adapt accordingly.
Now for the greatest part, card choices. Kolobok can be played over Mothmara, but not being able to trade naturally against anything actually really hurts. Vodnik Informant is also a valid choice. Ensaring serpent is more or less an efficient blocker with a sometimes reasonable effect, but now that brainstorm is only 1 blue, you may change them for one more thane and a babayaga's den, which fill the same rolls. Lastly, the one of marching orders comes in handy as a 1 cost spell that can remove blockers, get stuff or enchantments, and overall an efficient trick. However, it is not mandatory and can be replaced by other spells such as detained or led astray.
Overall, deck is fun, you hit people for too much damage because Allfather's Horn is still really good (and hard carries the deck), and you get to play Zira. If you have all the cards or this deck magically manages it's way into feature decks (which it isn't), I encourage you to try it out. Where else are you gonna be able to play Recursionist, Zira and Bela at the same time afterall? A good deck?