Mulligans
General Mulligans
Witchwood Piper is ideal in every situation, as it guarantees your curve for turn 4/5 when things start to get going.
Maelstrom Portal and Jade Claws are decent as they slightly help with board control in the early game. If you can't get Witchwood Piper, keeping a defensive like Feral Spirit can help stall until you draw what you need.
Blazing Invocation can be a good way to generate a low-cost minion for the early game, there's also the small chance you might get an extra Witchwood Piper or Muckmorpher.
Simplified, this deck relies on getting one of 4 cards out as soon as possible:
(Ancestor’s Call) or (Eureka!) if you haven’t drawn (Witchwood Piper) or (Muckmorpher) yet.
(Muckmorpher) if you’ve already drawn (Witchwood Piper).
(Witchwood Piper) if you haven’t drawn (Muckmorpher) yet,
If you’ve drawn (Muckmorpher) but not (Witchwood Piper), you’ll have to calculate your risks and make the decision that best fits the situation.
You could also substitute (Witchwood Piper) for a different card if you feel like something else would suit you better.