Tyrants of the Underdark is a territory control game with a deck-building element.
Each player leads a house of Drow in a section of the Underdark below the Sword Coast. The Drow house is represented by a deck of cards, with each card being a minion in that player's deck. Each minion belongs to one of five aspects of Drow society, and those aspects correspond to different strategies in the game, e.g., malice minions excel at assassinating opponents' troops, while ambition minions are best at recruiting additional minions and promoting minions to your "inner circle", which is a special zone that increases their value at the end of the game.
Players gain points by controlling sites, recruiting valuable minions, promoting minions to your inner circle, and assassinating troops, and whoever ends the game with the most points wins.
NOTE: This 2021 printing includes the Aberrations & Undead expansion.