The Final Gamble
Prerequisites: Wild Magic Sorcerer of 16th level or higher
Knows the Globe of Invulnerability spell
Knows the Demiplane spell
When you choose this feat, you may cast the Mephisto’s Final Gamble spell once per long rest, at the expense of an 8th-level spell slot. This does not count towards your amount of known spells.
Additionally, you gain proficiency in a game set of choice. If you are already proficient with a game set, you may choose to gain expertise in that set, doubling your proficiency bonus, or choose to gain proficiency in another set.
Mephisto’s Final Gamble
8th Level Conjuration
Components: V, M (a set of gem-infused dice worth at least 250 GP, which the spell does not consume)
Time: activates instantaneously, lasts until the effect resolves.
You choose one creature up to 30 ft. away. This creature must be able to speak at least one language. You and this creature are transported to another plane of existence, as per the Demiplane spell. The plane is a 30 ft. by 15 ft. round room, with walls covered in fine silk. The room contains two chairs and a table with unweighted dice and unmarked playing cards. A field of antimagic covers the entire room, and the effects of every damaging feature or otherwise harmful effect is nullified.
Upon entering this room, you and the other creature can understand each other. You must decide upon the wagers. The wagers must be fair; this is mostly up to the DM’s discretion. However, if both parties agree upon an unfair wager, it will continue. After this step, the game begins. Both creatures must sit around the table and decide upon the game.
The game is played, using the minigames detailed at the end, or another minigame if the DM finds it appropriate. After the winner has been decided, the winner gains what he wagered, and what the loser wagered. The loser loses his wager. Both creatures are teleported back to their positions before the gamble, without any time having passed.
Requirements: a set of dice
Decide upon whether the first to 5, 7 or 9 penalties loses.
Step 1: Each round, both players roll a d20, without showing each other the results after step 2.
Step 2: You have seen your roll. Both parties state their rolls. Now you have these options:
You make up any number for the dice roll. You roll a Charisma (Deception) check, contested by the opponent’s Wisdom (Insight) check. If you fail, you are caught, and automatically gain 2 penalties.
You add 1d6 to the roll (up to a maximum of 20). You roll a Dexterity (Sleight of Hand) check, contested by the opponent’s Passive Perception. If you fail, you automatically gain 2 penalties.
You try to make your opponent fall into checking your roll. You roll a Charisma (Deception) check, contested by the opponent’s Wisdom (Insight) check. On a success, your opponent gains 2 penalties.
When you use the same action for the second time, the opponent gains a +2 bonus to their check. When you use the same action for the third time, the opponent gains a +5 bonus to their check. When you use the same action four times or more, the opponent gains a +10 bonus to their check. This is reset when you use another action.
You may also choose to do nothing during your round. The opponent may also try to use these tactics, but that is at the DM’s discretion.
When you fairly win a round, your opponent gains one penalty.