Where are the rules for creatures attacking creatures immune to nonmagical weapon attacks?

Question

For Druid Wild Shape:

PRIMAL STRIKE Starting at 6th level, your attacks in beast form count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

For the Monk:

KI-EMPOWERED STRIKES Starting at 6th leveI, your unarmed strikes count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

The text seems to indicate the ability to bypass magical immunity requires a feature.

Alternatively, I have read that natural attacks and unarmed attacks aren't "weapons," and therefore you should just be able to pummel the Werewolf with your hands if your sword fails:

Melee Attacks (PHB p.195 (or in errata), emphasis mine). The rule on unarmed strikes should read as follows: “Instead of using a weapon to make a melee weapon attack, you can use an unarmed strike: a punch, kick, head-butt, or similar forceful blow (none of which count as weapons).

However the errata for Monster Manual I guess clears that loophole:

Global Damage Resistances/Immunities. Throughout the book, instances of “nonmagical weapons” in Damage Resistances/Immunities entries have been replaced with “nonmagical attacks.”

We temporarily ad hoc'd an answer in our game to say the Stirges summoned by the druid were magical creatures(Fey) and hence had magical attacks against the Werewolves, even though they were 1HD(d4). Now I see the druid made the Fey part up, and they are beasts, but oh well.

What is the real rule here?

Answer 1

The damage listed in a creature's stat-block does exactly what it says, nothing more.

The section of the monster manual covering how to interpret stat blocks is only about 10 pages long. In that section the only text related to what defines a magical attack I could find was on p.8 of the MM:

Particular creatures are even resistant or immune to damage from nomagical attacks (a magical attack is an attack delivered by a spell, a magic item, or another magical source).

Given this, fifth editions reliance on plain language, and the result of the question here, it appears summoned creatures, and creatures in general, including fey and PCs, only do nonmagical bludgeoning, piercing, and slashing damage, unless stated otherwise.

Also of note, there are no weapons beyond +3 in fifth edition, and a +1 or magical weapon is a much bigger deal than in previous editions of the game.

For unarmed strikes, with the exception of a level 6 or higher monk, they still count as bludgeoning, piercing, or slashing damage from a non-magical source. See the question and answer here.

Answer 2

RAW, a fight between Werewolves last until one of them collapses from dehydration or exhaustion

They can not hurt eachother. This does look stupid to me, but these are the rules for now.

Every edition of DnD is quite PC focused, this one more so. Describing and regulating interaction between monsters is not a priority for the authors, so I suggest creating some houserules.

Houserules

Option 1: Everyone can hurt itself without problems.
If a monster has resistance to non-magical weapons, its attacks are considered magical.

Option 2: Big and scary can hurt anyone.
Above a certain CR (I suggest 10) every monster hits as if magical.

Answer 3

Possibility: Attacks from any creature other than beast or humanoid are considered magical:

so aberration, monstrosity, dragon, etc. all count as magical for overcoming magic resistance. In additional humanoid subtype of shapechanger is considered to have magical attack when using its natural attacks. So a werewolf using a longsword couldn't damage another werewolf, but a werewolf using its bite could.

This explains why monk and druid must specify (since their forms are humanoid and beast)

However it does leave a door open for unusual races such as Shifter, and Changeling.