Mulligan: The Demon Seed, Kobold Librarian, Tour Guide, Crystallizer, Imprisioned Horror. If your opponent is more likely to be aggro, keep Spirit Bomb, Touch of Nathrezim and Dark Pact as well. Leave Happy Ghoul if you already have Nathrezim or Dark Pact, or you have the necessary cards to quickly complete stage 1 of the Quesline.
Imprisioned Horror can be played as early as turn 2 with 2 Crystallizers or 2 Kobold/1 Kobold+Tour Guide and a Crystallizer with a coin.

Think outside the box and if your opponent is slow, don’t feel sorry for your small minions and give them for example Spirit Bomb to complete the Questline. If you healed this turn, feel free to cast Spirit Bomb or Dark Pact (it will heal itself) in your Happy Ghoul if you have Raise Dead in your hand and you needed 2 minions to get the maximum value from this spell. So you immediately return Happy Ghoul to the board
If your opponent has destruction cards like Dirty Rat. Don’t rush through Stage 3 of the Questline. Better play next turn like Kobold Librarian to get Tamsin and cast it immediately.

As long as you have Crystallizer armor, your Flesh Giants won’t get any cost reductions from damage cards since your health doesn’t change. Keep this in mind when planning your move with Flesh Giant and Animated Broomstick.

Dark Pact is one of the best cards in the deck and I’m not kidding. It is very important for this archetype to have a lot of healing as you need to deal 30 damage to yourself in order to complete the Questline. Basically kill yourself. That’s why it’s so important to have enough healing to stabilize.

If you hate the secret of magicians, this deck will destroy them, if of course it is correct to win back from the secrets.

The hardest thing for a deck to do is matchup against Burn decks. Easiest against control or aggro decks with no direct damage from hand. It is quite possible to play against Mech Paladin. Especially with early Imprisioned Horror

In general, the deck is demanding on skills, no matter who hates the past of the archetype.

If you often come across combo decks. replace 1 Broomstick with Loatheb
You can also replace 2 ghouls with Smothering Starfish and Ashen Elemental. This replacement will improve matchups with Frog Shaman, Tony Druid, Quest mage and Mech Paladin

Good luck on the ladder