Deepwalkers

Deepwalkers are those who possess the ability to visualize and interact with the spectral plane while existing in the physical plane, which is known as Deep Sight. This ability is manifested in those with a deep spiritual or psychic connection, as well as those who have had a deep exposure to death and loss.
Kyra Goldenleaf is an example of a known Deepwalker.

Deepwalker Rulings

• If a character is a Deepwalker, that character is able to cast Speak with Dead as an action a number of times equal to their Proficiency Bonus per long rest. When the spell is cast, the Deepwalker is the only person able to see and hear the spirit.
• Some spirits, such as those of animals, may become attached to Deepwalkers if they had a close connection in life. These creatures gain the ability to pass through solid objects as if they were rough terrain. They also gain immunity to all damage, so long as the attacker is not on the same plane of existence as them.