Calculating HP for UA beast master animal companion

Question

I am a very new DM in DnD 5e, and one of my players is a ranger. As I was browsing through posts here and there we decided to use the UA, as everyone is saying the RAW ranger is lackluster. She obtained her wolf in a little side story, and I would like to set up the stats for her companion. I read through the UA, and it states:

For each level you gain after 3rd, your animal
companion gains an additional hit die and increases its hit points accordingly.

Now this confuses me a lot, and upon further looking into how HP is calculated, I don't even understand the stats of the simple Wolf enemy.

So in the Monster Manual the HP of the wolf is 11 (2d8+2).

First question: How is this calculated? The average of 2d8 should be 10. 10+2 is 12.

Second question: What is the hit die of a wolf? If its 1d8, than in case the wolf is "level 1", its HP should be 10 (max hit die + con modifier). If it is considered to be level 2, its HP should be 17 (Max hit die + avg hit die + con modifier). What am I missing?

Third question: I found a post on a DnD reddit site where someone calculates the stats of a wolf in case the ranger is level 7. It goes like this:

Wolf

Medium beast, your alignment

Armor Class 17

Hit Points 35 (6d8+6)

Speed 40 ft.

STR 12 (+1)

DEX 17 (+3)

CON 12 (+1)

INT 3 (-4)

WIS 12 (+1)

CHA 6 (-2)

Proficiency Bonus +3

Skills: Perception +4, Stealth +6, Skill of Choice, Skill of Choice

Saving Throws: Str +4, Dex +6, Con +4, Int -1, Wis +4, Cha +1

Senses: passive Perception 14

Actions Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d4 + 6) piercing damage. If the target is a creature, it must succeed on a DC 12 Strength saving throw or be knocked prone.

I think I was able to figure out everything, except the HP.

My first assumption was to start with the given base 11 HP as a level 3 companion. Than at level 4, it gains an additional 7 (5 hit die +con modifier). And the same thing goes on for level 5, 6 and 7, to a total of 11+4*7 totaling 39.

If I start from the 2d8+2, and just add a hit die each time the ranger levels up, I can understand the 6d8 mentioned in the post, but I don't get the +6 modifier. Shouldn't it be +10? +2 base modifier at level 3, and +2 for each 4 levels totaling at +10. And now the problem is that averaging this value leads to 40, not 39, this problem is coming from my first question.

I am completely lost here.

One last question. The Bite attack says +6 to hit. I can explain this as the DEX modifier became +3, and the proficiency bonus also became +3, however I dont understand the reason why DEX modifier is used for the Bite attack instead of STR.

Thanks a lot for the answer!

Answer 1

The UA Ranger's wolf companion

To answer your questions:

1. "The average of 2d8 should be 10. 10+2 is 12." This explanation by kriivi via a comment is better than my original attempt, so I'm going to quote it here:

   Expected value is linear, which means that the sum of individual die values will do. In the case of d8, the expected value (or more intuitively, average of possible outcomes) is 4.5, which means the expected value of 2d8 is simply 2*4.5 = 9.

2. Monsters and PCs use different rules, and as such, the number of hit die a monster has does not reflect its level in the same way that a PC would.

   For a better relationship between the "level" of a monster (CR) and its HP, there are rules in the DMG for creating and balancing monsters, in particular a table showing how HP, AC, damage output, etc, related to a creature's CR.

3. The +6 that they are adding to the monster's HP comes from the fact that it should add +1 per hit die, in the same way that PCs do (I know I just said that monsters and PCs don't use the same rules, but this is one of the cases where they do). Since a PC's HP (past first level) is hit die + CON modifier, that's what's happening here. It's plus 6 because the monster has 6 hit die, and a CON modifier of 1.

   As for the total value of 35, I've noticed with monsters, they tend to take the "overall" average hit die values (as per kriivi's quote above), rather than average 1 by 1 (like PCs do). So the average for 2d8 for a PC would be 10, but the average for a monster would be 9; hence the default wolf's total of 11 HP (9 plus the +2 from their CON modifier). For a Beast Master wolf, the first 2d8 were using "monster averages", hence total 11. From then on, the next 4d8 were done using "player averages", meaning +5 per hit die (so actually +6 because of the +1 from CON modifier). Hence the total HP is 11 + (6 × 4) = 35.

Lastly: Some monsters use DEX instead of STR for their attacks, particularly if it's a "natural weapon" (like a wolf's bite). This appears to be the case here.

Using the RAW Beast Master

If the UA seems a bit complicated (given that you're a first time DM), I'd recommend using the RAW Beast Master in the PHB (the HP calculation is a lot simpler, since it's just 4 × ranger level), but with the following houserule:

Use a bonus action, instead of an action, to command the beast to attack.

This houserule has been suggested in an article on D&DBeyond.

This houserule has been also discussed on RPG.SE before, see: If Beast Master Rangers could use bonus actions to attack with their companion, what problems would occur?

I answered that question too, since my first time DMing was also for a player who made a Beast Master ranger, and it worked well for us without making the character overpowered, but without feeling as underpowered as the RAW Beast Master without this houserule.

Answer 2

First

The average (expected value) of 2d8 is 9, not 10.

Second

The rules for monsters and PC-s are separate. There is no such thing as a level 1 wolf (unless you awaken it to sentience and it gains a PC level). You are correct that its hit die is a d8.

Third

To me it seems that either they miscalculated or are using different rules than you are (homebrew, table rules...). I believe your HP calculations are correct.

Last

See monsters just being monsters, as above. The creators considered the wolf's jaws a finesse weapon.