Lich - Wizard

The most known type of Lich, and therefore the one that holds the namesake, is when a Wizard performs the ritual

The Phylactery is the most basic type where the caster attaches their soul to an object, usually one of personal value. Liches are extremely protective of their phylactery and will layer them with traps, enchantments, and all manner of ways that only the Lich itself can reach. These Lich's are known for their vast intellect and superiorly evil magics, creating plots that can take decades to complete or even start. A common tactic of the Lich is to simply outlive their foe rather than confront it

The Lich need only maintain themselves with a ritual when they "die" and reform themselves. The ritual this time around is similar but shorter and easier to perform for the Lich, it can be completed in less than a day. The Lich becomes vulnerable only in the sense that it is now mortal and if killed again, it will be dead for good. Additionally, the longer the Lich takes to re-anchor themselves to their phylactery, the greater the chance they become a Bone Claw. Each time the Lich performs the ritual to anchor themselves again, they remove more and more of their being, losing more of who they originally were. This reason alone is why the Lich prefers seclusion rather than risk needing to recast the ritual

The Lich's strongest asset is its seclusion and superior intellect. They build high towers or deep caverns that are guarded by powerful enchantments and various creatures or creations to protect it. They are by far one of the most powerful non-innate arcane casters in the material plane. Their main weakness is their own rituals. As mentioned before, the more a Lich has to redo their rituals, the more they lose who they were. As their power grows so does their ego and they may lose their sense of self preservation. Their schemes and plans may be more grandiose as their interests changes and they want to be known. As the fable or rumor of a Lich becomes known as fact, nations and agencies would be quick to move and strike against it