Your spirit's senses overlap yours, so you lose any senses you possess that your spirit doesn't possess with exception to your ethereal sight.
At level 7 your spirit's attacks are considered magical for the purpose of overcoming resistance and immunity against non magical damage and attacks.
When you reach 11th level, you gain temporary hit points equal to your shaman level when you become possessed. These hit points last until the end of the possession.
Note: changes in Dex or Con do not affect your AC or HP and only apply for the sake of checks, saves, and attacks.
When you use your action to make an attack from your possessing spirit it appears as a spectral apparition of the attack, and while you deal the damage type and dice of the attack, you still use your weapon on the attack, so, if you use a ranged weapon, like a bow, you can still make any attack from your spirit, like a bite attack. Also, any extra damage, or bonus to attack rolls you gain from magical weapons still affect your spirit attacks. You can use any number of your attacks to make spirit attacks. If you cast a spell you can then use your bonus action to have your possessed spirit attack.
You can maintain the possession by a number of hours equal to half your shaman level (rounded down). You then end the possession unless you expend another use of this feature.. You can also end the possession with a bonus action in your turn. You automatically end the possession if you fall to 0 hit points, or die.
While you are possessed, the following rules apply:
Some of your game statistics are replaced by the statistics of the beast whose spirit is possessing you. Those being, its Strength, Dexterity and Constitution scores, its attacks, its senses and any other personal features. You don't gain its hit points, AC, or any special types of movement (like flight)
At 2nd level, you can use your action to enter a trance and allow a beastly spirit to possess your body, giving you the abilities of the spirit. You can use this feature twice. You regain expended uses when you finish a short or long rest. (Optional Rule: the Shaman must have collected the spirit of the animal you wish to channel. to collect you must be aware of the spirit of a creature that meets the requirements and succeed on an animal handling check. When using this rule some monstrosities such as winter wolf may be allowed)
Your shaman level determines the spirit that can possess you. You can be possessed by the spirit of a beast with a CR of no more than half your shaman level (rounded down). When you channel you do not gain lair actions or legendary resistances.