Dungeons & Dragons will be exploring new ways for players to spend their Hit Dice in-game, as they are currently restricted to a single aspect of play. Hit Dice are a reflection of the character's level and the dice they use for their maximum hit points, so a level three warlock would have 3d8 Hit Dice, which increases to 4d8 when they reach level four.
Hit Dice are used as part of D&D's short rest and long rest mechanic. A short rest generally lasts for around an hour and players can roll their Hit Dice in healing, so a level four Warlock could choose to heal 2d8 of their Hit Dice, and save the remaining 2d8 for a future short rest. A long rest requires eight hours of rest, but it fully restores all lost hit points and refreshes any spent Hit Dice. The vast majority of a character's special abilities are only refreshed upon a long rest, so the players always need to be careful about blowing through their powers too quickly.
The D&D 5e rules have received updates in different ways, and Hit Dice could be the next element of the game to be expanded. D&D Principal Rules Designer Jeremy Crawford has revealed on the Dungeons & Dragons YouTube channel (via. ComicBook.com) that they are exploring new ways to use Hit Dice. The full video can be found below:
There has already been an example of Hit Dice being used in new ways in D&D, albeit in playtest material that has yet to be officially printed. There was an Unearthed Arcana article that introduced elements from the Dragonlance campaign setting into 5e. The article featured elements like the kender race and the Lunar Magic subclass for the sorcerer. The Dragonlance article featured new backgrounds, one of which is the Adept of the Black Robes. This background grants the Life Channel ability, where the character can target a foe that has failed a saving throw against one of their spells, and spend their Hit Dice to deal additional damage to them.
The expansion of Hit Dice is a great concept, as it can be used to strengthen character abilities, at the risk of losing out on potential healing further down the road. The D&D 5e rules have received a lot of tweaks recently and fans have noticed a power creep among backgrounds, classes, and races. It's possible that a lot of elements of the game are being reworked, as part of the D&D 5.5 rules update that is arriving in 2024, to mark the 50th anniversary of Dungeons & Dragons.
Source: Dungeons & Dragons/YouTube, ComicBook.com