So I'm heavily referencing the Rider-Waite deck for this since it is the quitessential Tarot deck.
The original card looks like this. But imagine that the dog and the wolf are replaced by Autumn and her Other Half. The crayfish is replaced by fireflies, and the two pillars are replaced by the city and the forest. The liquid pouring from the moon represents "the descent of the Life-Force from above into the material existence." (Wikipedia) Basically the Moon card is a very heavily psychoanalytical card, IMHO. And it's entire theme of uncovering hidden knowledge in order to grow seems to really resonate with Autumn's character. In my version, Autumn herself represents the domesticated human form and waking consciousness, while the werewolf represents the primal, the subconscious. Her kneeled position indicates supression, and the heart in her hands indicates emotion. Conversely, Autumn is holding a skull which symbolises knowledge (or death, I guess, but here it's more knoweldge. ) Together they represent the core of Autumn's character; she is intelligent and fairly self-aware but represses her more primal urges and emotions since it's what she's been taught to do in order to survive. The fireflies represent primitive life but their illumination indicates that discovery can be learned from all things. Towering in the distance is a forest and a city, which sort of compounds on the whole civilzation vs wilderness dichotomy found in the presence of Autumn and her Other Half. Their height in particular could be said to represent the vast heights that one most climb in order to obtain the knowledge hidden beyond the Moon. Which herself symbolizes the subconscious, mystery, and deep understanding. I'm thinking of doing a series of themed commissions like this. Commissioners would choose a card from the Major Arcana and offer an explanation as to why they think the card suits their character(s) so as to make it easier for me to design the card.