"your claw rusts and falls off after you tear into the rust monster."
It's called a Circle of the Moon druid.Essentially, ‘Rule Zero’ means, the rules have not yet supported the archetype.
No, it isn’t. They aren’t the same thing.It's called a Circle of the Moon druid.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.