Lich info

So here's the skinny on Liches. Most people probably -wouldn't- recognize a phylactery, but someone who's had dealings with underworld entities might have seen one in their day collected as a sort of trophy. That, and clergy of Ioun or the Raven Queen might pick up on it too.

There aren't many liches in the world. The process involves binding your life force to the phylactery, and in the meantime you need to have another form of energy to animate your body after you've pushed your soul out. There's a few different ways of doing this, and these are some of the ways Silver or Lycoris would have heard:

The most heinous -  Slaughtering innocents in a ritual to convert THEIR life force into a sustaining force for your body. This is the classic type that legends warn of.
The thief - In the underworld, there are sources of power in the form of a liquid energy. The Stygian Flow is a river made of this energy, which helps to sustain spirits of the underworld and guide them to their final rest. A living being that drinks this 'water' will gradually accumulate enough energy to sustain their form without their soul present in their body. The denizens of the underworld seek out those that steal this energy because it serves to weaken and delay the passing of mortal spirits. Indistinguishable appearance wise from the first type of lich.
The least seen path - Absorbing primal spirits, willingly or not. The type of Lich that forms from this is called a Baelnorn and tends to look like they did in life, though somewhat gaunt.