The Sight

The Sight is an main quest in Fallout 4.

Detailed walkthrough
After giving her Jet she will request that the player character make her a special chair called Mama Murphy's chair. She will continue giving vague, but ultimately true predictions with more and more basic chems, such as Buffout, Mentats, Med-X and Psycho. These predictions unlock new dialogue options that allow the Sole Survivor to avoid combat during main quest line missions, namely Nick's rescue and the standoff with the synth courser.

After asking for Psycho and delivering the prediction that follows, she will die, making all of the Minutemen mourn her death.

Alternatively, the Sole Survivor may pass one of two hard Charisma checks to convince her to give up chems entirely, at which point she will lose the Sight, and not offer this service.