Circle of the Full Moon

[Loek]

Like some have said already, this is a cool idea but is also a bit cumbersome for what you are after. One idea is to look at the build of lychanthrope monsters and incorporating the common elements of them. There is also the consideration much like the lychanthrope monsters are you going to allow the use of weapons a druid has access to while in their hybrid shape? More so how do you balance this?

The main problem with straight up looking at the lycanthropes, is the fact that they true transformations (Think brackets around that true bit there). If a lycanthrope hits 0 HP, it dies, while a druid merely shifts back to their normal form. As such, looking at the beasts (that a druid's wildshape is supposedly balanced for) makes more sense (and later the elementals for the level 10 feature).

As for weapon use, I'd consider letting them use weapons, but only by replacing one of their attacks. Which in almost all cases (levels/weapons) would lead to a strictly weaker attack as the shape's damages quickly outstrip the druid's limited weapons (not to mention the specials attached to quite a few beast attacks). The main win would be if you go ranged weapon, which will need an outside source of proficiencies (No (cross)bows for the druids) to truly shine. And even then, a shifted druid can't use their magic. So they are already giving up a massive source of ranged options.

One idea/example may be something like this:
...

I really like the simplicity of this write up. A simple few rules instead of reinventing the wheel. Very nicely done.
However, let's take one of the more advanced forms. Like the Giant shark. In hybrid form, they'd be sacrificing their swim speed (but still need to breathe underwater) and their 3d10 attack for a very basic normal attack.

Realistically, it would result in a normal Moon druid, but with an additional hybrid "utility" trick.

And as I stated in my design goals, the goal was to temper some of the Moon druid's complexity and strengths. Not add to them.

On your Lycanthropic Wild Shape I would just make it a support ability granting immunity the resistance to the weapon damages but with the caveaut of being non-magical and non-silver. This falls in line design with like with the resistance abilities the paladin gets.

Like I said above, I'm comparing this ability to the "elemental wildshape" ability. But even if you compare it to the paladin (I'm guessing the oathbreaker's 15th level one?):

• The paladin's ability is always active and has one less "way around it".
• The druid one reduces one of their core features from a twice a rest to a single use per rest.

So no, I wouldn't limit it to just that resistance.

All that said, this sentence looks near perfect, and I'll be borrowing that one (though I'll let them substitute regardless of multi attack):

• If your animal form grants you a multi-attack you may substitute one attack with a weapon attack that is a melee weapon you are proficient in. You must declare this substitution prior to making the attack.