I didn't get a hex for Lucky; is it missing? How do I play him since he doesn't have a hex?
The player with Lucky gets to choose the home Hex tile.

The Crystal Crypt shorthand on the Hex Reference Sheet says: "+1 Purple Gem, NO DMG TAKEN" but the text listed underneath says. “If you start your turn on this Hex tile, add a Gem to your Resource Pool. If an enemy deals DMG to you while you’re on this Hex tile, you cannot reduce that DMG.“ What should I do?
The shorthand is incorrect. Players located on the Crystal Crypt Hex tile cannot reduce incoming DMG.

Should I remove expansion cards if none of the expansion characters are being played?
No, you do not need to play the expansion characters provided in the expansion to enjoy the cards.

How often can I CAST each one of my Spells during my turn?
Each Spell card can only be CAST once per turn. After a spell has been CAST, you must wait till your following turn to CAST it again. Bonus clarification: When a player CASTS a Spell card, it remains in the player's Spell Book but cannot be CAST again until their next turn.

In a scenario where Player A’s health is reduced to 0, but they have a way to return DMG to the attacking player, and the returned DMG would kill the attacking Player, what happens?
The rules state, “If at any point your HP reaches 0, you are immediately eliminated from the game; move all the cards in your Spell Book to the discard pile” In other words, the return DMG would not take place because Player A was attacked first, and their HP was reduced to 0, immediately eliminating them from the game.

Can you gain health past 18?
No, you cannot.

Does it cost one action point when I use my character's special ability?
No, using your Character Ability does not cost an Action point. "Shadow Form also grants you access to your Character's unique Ability, which you can use by spending Shadow Energy. You may use your Character's Ability during Phase 2 of your turn, and doing so does not cost an Action point."

Can I save unspent resources for my next turn?
No, your Resource Pool empties at the end of your turn.

Can I ever return to Base Form once I transform into Shadow Form?
No, you cannot return to your Base Form once you’ve transformed to your Shadow Form.

Do I have to spend one action point for each die I want to Reroll?
No, you can Reroll as many dice as you’d like when you use the Reroll action as long as they are not Cursed Crystals.