Blackjack dragons dwell in swamps on the frayed edges of civilization, and in the heart of undercities. A blackjack dragon makes its lair inside dismal caves, grottoes, ruins, or sewers that are at least partially flooded, providing pools where the dragon rests, and where its victims can ferment. The lair is littered with the acid-pitted bones of previous victims and the fly-ridden carcasses of fresh kills, watched over by crumbling statues. The air inside is dense with dancing lights and the smell of alcohol and combustible intoxicants.

Blackjack

To play this creature to full effect, have at least 2 decks of cards and a set of chips. Like in normal Blackjack, face cards have a value of 10, and Aces have a value of 11 or 1. Every other card is worth its printed value.

On the first initiative count 21 (losing initiative ties but before Lair Actions), the dragon draws 2 cards from the deck. Place one face up and one face down in view of the players.

At the end of a player's turn, ask them how much they would like to bet (not betting is an option). Then deal them 2 cards face up for the other players to see. The player may hit as many times as they like or stay. If a player hits and their hand exceeds 21, they immediately bust, taking 4d6 acid damage and losing their bet chips. Be sure to keep things moving quickly!

On every initiative count 21 after the first, flip your face-down card over. Continue drawing cards face-up until your hand value is 17 or greater. If you hand is worth a soft 17 (for example: an ace and a 6 or an ace and a 4 and a 2, etc.) continue hitting until you have a hand worth more than 17 (for example, you hit a soft 19 by drawing a 2), or you get a hard 17. If your hand is worth more than 21 once you've finished drawing, you bust. Give each player who has not busted an Inspiration Chip (IS). They can use these to reroll any of their attack, check, or saving throw rolls and take the higher result. If you do not bust, each player with a higher value hand is given an Inspiration Chip, each player with a lower value hand takes 4d6 acid damage, and each player with an equal value hand will take no damage and receive no chip.

If a player wins the hand, they will win the number of bet chips plus the regular winnings. For example, if a player has 2 Inspiration Chips and bets both of them and wins the hand, they would receive 3 Inspiration Chips in return; 2 from the amount they bet, and 1 for the acid damage they would have taken if they lost.

If a player gets a Blackjack (a 2-card 21 consisting of a 10-value card and an ace), replace each Inspiration Chip they would have won with a Critical Success Chip (CSC), which they can use to turn any of their attack, check, or saving throw rolls into a natural 20. If they get a Blackjack and bet a Critical Success Chip, treat each Critical Success Chip as 3 Inspiration Chips. For example, if they bet a Critical Success Chip and get a Blackjack, they would win 4 Critical Success Chips (given 1 Critical Success Chip = 3 Inspiration Chips, and each Inspiration Chip would be converted to a CSC, plus 1 more for winning against the acid damage). However, if you also have a Blackjack, they will take no damage and receive no chip. In this case, players who have a hand worth 21 will lose to your Blackjack, taking 4d6 acid damage and receiving no chip.

Simply put, on a regular winning hand, give the player the Chips bet plus 1 Inspiration Chip and let them keep their bet chips. On a loss, they lose their bet chips and take acid damage. On a tie, nothing happens. If they win with a Blackjack, give them 1 CSC for each IS they would have won, and 3 CSCs for each CSC they would have won.

At any time, a player may cash in their Critical Success Chips into 3 Inspiration Chips and vice-versa. A player may also use their reaction to give another player a number of chips. This may result in players chaining Inspiration Chips and reactions on a single roll. For example, if a player fails her saving throw, another play may use his reaction to give her a chip, which she may use to reroll her save, potentially turning the failure into a success.

Lair Actions

On initiative count 21 (losing initiative ties and after Blackjack), the dragon may use a lair action to cause one of the following effects; the dragon can’t use the same effect two rounds in a row:

• Booze Spill. Toxic material erupts from the ground at a point the dragon chooses within its lair, covering a 15-foot radius circle on the ground. The area is considered difficult terrain, and any other creature standing inside must succeed a DC 16 Constitution saving throw or be poisoned until the end of their next turn. The first time a creature attempts to walk through the area, they must succeed on a DC 15 Dexterity saving throw or fall prone.
• Mesmerize. Mesmerizing lights engulf a point the dragon chooses within its lair, filling a 15-foot radius sphere until the next lair action. Any creature who enters the sphere must succeed on a DC 15 Wisdom saving throw or fall under the effects of the Slow spell (their speed is halved, they receive a -2 penalty to their AC and Dexterity saving throws, they cannot take reactions, they cannot take both a Bonus Action and Action, they can only make 1 attack if they take the attack action, and if there is a 25% chance a spell cast with a Somatic component will fail as the gestures required to cast the spell are done too slowly) until the end of their next turn.
• Secondhand Smoke. A thick haze forms at a point the dragon chooses within its lair, creating a 20-foot radius sphere. Anything within the haze is Heavily Obscured. The sphere lasts until it is dispersed by a strong wind or another haze is created.
• High Heat. Each creature in the dragons lair with 4 or more chips must succeed a DC 15 Wisdom saving throw or be frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. 

Regional Effects

The region containing a legendary Blackjack Dragon’s lair is warped by the dragon’s magic, which creates one or more of the following effects:

• The land within 6 miles of the lair takes twice as long as normal to traverse with navigation due to the dancing lights and supernaturally thick foliage and muck. Creatures without a means to navigate often lose their sense of direction and find themselves inside the lair.
• Valuable objects within 3 miles of the lair seemingly disappear without cause, only to end up in the hoard.
• A smoky haze fills the air within 6 miles of the lair.

If the dragon dies, vegetation remains as it has grown, but other effects fade over 1d10 days. Valuables lost must be retrieved from the hoard.