Mulligans
General Mulligans
This decks dream curve is as follows:
Turn One: Novice Zapper
Turn Two: Spirit Claws
Turn Three: Primal Dungeoneer
Turn Four: Sandbinder or Primal Dungeoneer
Then you might want to wait a turn or two until you have enough damage in hand.
Lightning Bloom is very helpful for comboing as it lets you play other spell damage minions or more spells the turn your phoenix's are summoned.
Aggro Mulligans
Devolve helps with pirate warrior and deathrattle decks.
A good Landslide with Squallhunter or Novice Zapper can easily win an aggro match up
Midrange Mulligans
This deck for being a combo deck can hold its own against midrange decks with its large overload minions Squallhunter stands out as it usually survives on curve and can be followed up with a devistating Landslide
Don't be afraid to use some of your damage spells on minions. It can be better to win on board than combo in some games.
Control Mulligans
Devolve helps with big Shaman/Priest/Warrior
Otherwise control is one of the best match ups for this deck just mulligan for combo
Kill your opponent 30 to 0 with nature spells