Your Wisdom score increases by 2 and your Constitution and Dexterity scores increase by 1.

In order to tell their age, Alexander the Great ringed a number of deer; when they were recaptured a century later they showed no sign of old age. If deer have few or no teeth, it shows that they are old. 

Deer technically live for only 20 years, but your innate magics allow them to reduce their own age. See the Enemy of Snakes feature for details.

The members of the holy Church seem to have a mentality corresponding to that of deer, because while they change their homeland, that is, the world, for love of the heavenly homeland, they carry each other, that is, the more perfect bring on and sustain the less perfect by their example and their good works. And if they find a place of sin, they leap over it at once, and after the incarnation of the Devil, that is, after committing a sin, they run, by their confession, to Christ.

Deer are usually neutral good.

Deer are medium-sized.

When they cross great rivers or large long stretches of water, they place their head on the hindquarters of the deer in front and, following one on the other, do not feel impeded by their weight. When they find such places, they cross them quickly, to avoid sinking in the mire. When the young grow strong enough to take flight, the deer train them to run and to leap great distances.

You have a walking speed of 30 feet and a swim speed of 20 feet.

Of their horns, the right-hand one is better for medical purposes. If you want to frighten off snakes, you should burn either. By burning one of your shed horns you can cast cause fear on any serpent. Serpents include snakes, lizards, dragons, and all their close relatives. (Basically any reptile other than birds.) When you burn the rightmost horn, the resulting spell also ignores any innate immunity to the frightened condition.

You shed two horns each season. The horns lose their potency after a season, so you can only ever have a stockpile of two.

Deer are immune to the poisoned condition.

Deer are immune to diseases that cause fevers.

They have shown the value of the herb dittany, for after feeding on it, they shake out the arrows which have lodged in them.

When you eat fresh dittany from the ground, you can cast cure wounds on yourself, using your Wisdom score, as part of the same action.

Deer are the enemies of snakes; when they feel weighed down with weakness, they draw snakes from their holes with the breath of their noses and, overcoming the fatal nature of their venom, eat them and are restored. The rennet of a fawn killed in its mother's womb is a marvellous remedy against poisons. They have another characteristic, that after eating a snake they run to a spring and, drinking from it, shed their long coats and all signs of old age.

As an action, a deer can eat a snake out of a hole and choose to cast greater restoration or reduce their current age by 1d8 years. Their age cannot be reduced below adulthood with this ability.