Mulligans
General Mulligans
Bloodbloom is the only combo piece that gets blown up by Hemet, so it's an always keep. Sense Demons gives you Witchwood Pipers, which draw Emperor and Hemet, the two most important pieces.
Combo Mulligans
With one Emperor tick, we can play Mecha'thun and Bloodbloom on the same turn, which lets us cheat out Cataclysm as long as we have more then 5 health.
This is a terrible idea, but so terrible it just might work! How does this combo work? Well, if you reduce both Mecha'thun and Bloodbloom once with Emperor Thaurissan, you can play both on the same turn, allowing you to cast Cataclysm on the same turn.
In order to achieve that dream, I’ve filled the deck with cheap spells that will get blown up by Hemet, Jungle Hunter, allowing you to draw into your combo pieces. Running minimal minions makes Witchwood Piper more useful, and we can tutor them with Sense Demons, ensuring we get our important pieces faster.
This probably won’t work, but who knows!