Why record number of Hit Dice?

Question

Brand new to D&D 5e and trying to wrap my head around the accumulation and spending of Hit Die. My understanding is that:

• Hit Die are used to determine your character's Max HP
• Hit Die are gained for each Character Level you gain
• Hit Die are determined by your class plus some modifier for example a Cleric might have a d8 Hit Die and roll 1d8+3 each time the character gains a Level
  • If I'm Level 3, I have three (3) d8 Hit Die and have, say, 40 Max HP
  • If I Level up to 4, then I get a 4th d8 Hit Die, roll it and say it rolls a 5. I add 5 + 3 and my max HP is now 48

If anything I've said above is incorrect or slightly misled, please begin by correcting me (and as an aside to my actual question, I'd love to know where that +3 modifier is coming from! I thought it was supposed to be the Constitution modifier but I got this from a Lost Mines of Phandelver Character Sheet for a Cleric 1 but his/her CON modifier is +2, so not sure where +3 is coming from!).

Assuming I'm more or less correct, I'm not understanding why we need to keep track of how many Hit Die we have (why there's a space for recording it on my Character Sheet). And I'm not understanding how these accumulated Hit Dice are "spent" when I want to replenish some lost HP during and/or after combat, nor how to "replenish" spend Hit Dice. Can someone help point me in the right direction here?

Answer 1

Hit Dice for Maximum Hit Points

You are correct that the Constitution modifier is added to hit dice when rolling hit points. The hit die itself is just the size of dice: a Cleric gets d8 hit dice, and with a Constitution modifier of +2 would start with 10 hit points and gain 1d8+2 hit points per level. But there are some specific rules - usually features, traits or feats - that modify or add to this calculation.

In this case, the Cleric in the Starter Set is a Hill Dwarf, and as such has the Dwarven Toughness trait. It’s written on the character sheet in the “Features & Traits” section, but for ease of reference:

Dwarven Toughness. Your hit point maximum increases by 1, and it increases by 1 every time you gain a level (included).

So effectively they gain 1d8+3 additional hit points when they level up. (“(Included)” means these extra hit points are already included in the character’s stats.)

Using Hit Dice in Play

The reason you track the number of hit dice is for healing during short rests. As per the rules for Short Rests in “Chapter 8: Adventuring” of the Basic Rules:

A character can spend one or more Hit Dice at the end of a short rest, up to the character's maximum number of Hit Dice, which is equal to the character's level. For each Hit Die spent in this way, the player rolls the die and adds the character's Constitution modifier to it. The character regains hit points equal to the total (minimum of 0). The player can decide to spend an additional Hit Die after each roll. A character regains some spent Hit Dice upon finishing a long rest, as explained below.

So hit dice function as a resource you spend and regain in much the same way as spell slots or limited-use abilities. While they’re sometimes overshadowed by magical sources of healing and the full healing provided by a Long Rest, they’re still very useful, especially if the party has to fight a lot during a single day.

There are other traits and features that can modify healing with hit dice, too, though none appear in the Starter Set.

Answer 2

Max hit points is calculated as (hit dice) + (Level x CON mod).

Sort of. “(Hit dice)” in my header there means something like “the sum of the results you rolled at each level up”. The rules for increasing your hit points when you gain a level state:

Each time you gain a level, you gain 1 additional Hit Die. Roll that Hit Die, add your Constitution modifier to the roll, and add the total (minimum of 1) to your hit point maximum. Alternatively, you can use the fixed value shown in your class entry, which is the average result of the die roll (rounded up).

When your Constitution modifier increases by 1, your hit point maximum increases by 1 for each level you have attained. For example, if your 7th-level fighter has a Constitution score of 17, when he reaches 8th level, he increases his Constitution score from 17 to 18, thus increasing his Constitution modifier from +3 to +4. His hit point maximum then increases by 8.

You don’t roll your hit die at 1st level, but for each level gained beyond 1st, you either roll or take the average (depending on what rule your DM is using) and add your constitution modifier to get your new maximum hit points.

Hit dice can be spent on a short rest, and up to half are recovered on a long rest.

The rules for short rests state:

A character can spend one or more Hit Dice at the end of a short rest, up to the character's maximum number of Hit Dice, which is equal to the character's level. For each Hit Die spent in this way, the player rolls the die and adds the character's Constitution modifier to it. The character regains hit points equal to the total (minimum of 0). The player can decide to spend an additional Hit Die after each roll.

And the rules for long rests state:

At the end of a long rest, a character regains all lost hit points. The character also regains spent Hit Dice, up to a number of dice equal to half of the character's total number of them (minimum of one die). For example, if a character has eight Hit Dice, he or she can regain four spent Hit Dice upon finishing a long rest.

So you can spend as many hit dice as you like on a short rest to recover hit points, but you can only recover at most half your maximum hit dice on a long rest.

In parties where healing magic is unavailable, or in campaigns where the DM runs numerous combat encounter between long rests, hit dice are extremely valuable because they can provide the only source of healing in certain situations.

Answer 3

I'd love to know where that +3 modifier is coming from! I thought it was supposed to be the Constitution modifier but I got this from a Lost Mines of Phandelver Character Sheet for a Cleric 1 but his/her CON modifier is +2, so not sure where +3 is coming from!

You are correct, it is from Constitution. The Cleric is also a Dwarf with Dwarven Toughness:

your hit point maximum increases by 1, and it increases by 1 every time you gain a level (included).

So that is 1d8 + 2 + 1 = 11 Hit Points at first level.

how these accumulated Hit Dice are "spent" when I want to replenish some lost HP during and/or after combat, nor how to "replenish" spend Hit Dice.

You may recover hit points with a 1 hour short rest by rolling your Hit Dice (e.g. 1d8) and adding your Constitution modifier. You may recover up to half your Hit Dice with an 8 hour long rest.

Hit Dice, and the spending/recovering mechanic with rests, are new to 5th Edition D&D. Prior editions used magic items or other tools to effect healing. Some other abilities were usable once per day per Hit Dice. But there was a lot of similar terms with those editions (Level Adjustment, Hit Dice, Racial Hit Dice, and Effective Character Level), so hope was that it was an easier concept to get a handle.