[RPG] Why do we assume that PHB rules apply to monsters


The party is deep into my 5e-updated classic Greyhawk Giants series.

They are returning the body of a stone giant killed in the siege of Headwater to the stone giant's clan. The Thane of the Stone Giants intends to hold Funerary Games in honor of his slain kinsman and invite the PC's to participate. One of the games will be unarmed combat.

In calculating an unarmed strike from a stone giant, I understand that the damage from the strike will be 7 points (1+ the stone giant Str mod). For the attack roll, however, I was unsure of whether to give the stone giants their proficiency bonus.

This question about unarmed bugbears, this question about unarmed skeletons, and this question about unarmed Flameskulls (?!), all have answers which state that monsters get to add their proficiency bonus to unarmed attacks, with the last question's accepted answer stating as a general principle that "creatures always have proficiency with their unarmed strike".

As justification for this position, these answers cite some variation of the Player's Handbook, PHB errata, or D&D Beyond, quoting "You are proficient with your unarmed strikes." None of the comments question this justification, and some support it.

Perhaps it is because I came to 5e from earlier editions, but my working assumption is that monsters / NPC's have stat blocks, not character levels, and don't necessarily follow the rules in the PHB. I read "You are proficient" and I feel like 'you' means 'You PC's', not 'All creatures'. I don't see anything in the Monster Manual that says that monsters in general follow the rules of the PHB or are proficient in unarmed strikes; I do see sidebars noting that monsters are proficient with their "armor, weapons, and tools" and that grappling rules work differently for many monsters compared to PC's.

Under the general principles of "there are no secret rules", and "abilities do what they say they do", where can I find a general statement saying that monsters follow the rules of the PHB, and that such "you" statements apply to them as well?

Related: Are monsters subject to the massive-damage instant-death rules?
The topmost answer to this question is "Combat rules apply to everyone". The second most upvoted answer is "Rules only apply to monsters if the DM wants them to." This doesn't seem like the consensus that greets the unarmed strike rule, which is why I wonder if this is indeed a general principle.

Related: Is the telepathy rule in the Monster Manual only applicable to monster telepathy abilities?

Best Answer

If monsters don't follow the "you" rules in the PHB, then many things become undefined.

You can make an opportunity attack when a hostile creature that you can see moves out of your reach.

Can monsters make opportunity attacks?

You can avoid provoking an opportunity attack by taking the Disengage action.

Can monsters disengage?

When you want to grab a creature or wrestle with it, you can use the Attack action to make a special melee attack, a grapple.

Can monsters grapple (when they don't have a special-case grapple attack in their stat block)?

If you're surprised, you can't move or take an action on your first turn of the combat, and you can't take a reaction until that turn ends.

Can monsters be surprised?

On your turn, you can move a distance up to your speed and take one action.

What can monsters do on a turn?

Thankfully, we have a clear answer in the intro to the combat chapter.

This section provides the rules you need for your characters and monsters to engage in combat, whether it is a brief skirmish or an extended conflict in a dungeon or on a field of battle. Throughout this section, the rules address you, the player or Dungeon Master. The Dungeon Master controls all the monsters and nonplayer characters involved in combat, and each other player controls an adventurer. “You” can also mean the character or monster that you control.