So you’ve heard of those wacky ideas about liches using forests, people, etc for their phylacteries...but what if doing such a thing is not advised because it risks altering the lich in unforseen and fundamental ways?
A lich does the trick where he makes a seed his phylactery. The seed grows into a tree, and that tree spawns a forest. As this goes on, the lich becomes aware of everything in the forest, as his soul permeates it or at least is bound to it. He starts to feel protective of the forest and become more and more engrossed by nature and life. He is not being a parasite in the forest taking a ride in it, no, he is becoming the soul of the forest and its walking avatar. Eventually his body is absorbed into nature.
A lich decides to make a phoenix her phylactery. The phoenix actually agrees to it because they know what will eventually happen to the lich. The phoenix’s celestial spirit will eventually bombard the lich with positive energy, slowly evicting the lich’s tie to them. Or something stranger can happen, the lich and the phoenix might eventually share their bodies, and there may be a conflict between their souls if the phoenix is good and the lich is evil. Or they could eventually merge together as a single being, the result being a very powerful undead phoenix.
A lich makes their phylactery a group of unsuspecting, innocent people. They know they would have to eventually re-create it as the people die, but boy is it clever, right? Except the group of people start to get plagued by the presence of the lich’s soul, however the people collectively have more souls than a single lich does at any given time. So the people’s souls start to influence the lich’s and the lich starts to become an insane amalgamation of all of those people’s personalities together.
The lich ties their soul to the sun, or the moon maybe. They eventually become absorbed into the moon or sun’s spirit, even moreso if their spirits are literal deities.
A lich binds their soul to a certain spell, or even a song. However now all that lich can do is sing or play that song or cast that spell for much of the rest of their days. Or their being starts to embody certain features of the song or spell.
@probablynecromancerrpgideas