Steps to Complete St. Trina’s Questline
Speak to St. Trina at the Stone Coffin Fissure:

Location: Stone Coffin Fissure, accessible from the southern tip of the Cerulean Coast. Ascend the cliff to find a hole leading down to the fissure.
Imbibe the Nectar:

Objective: Interact with St. Trina and imbibe the nectar six times. Each time you drink, you’ll die instantly but gain crucial dialogue from Elden Ring Items St. Trina. The first four drinks will provide significant dialogue, while the fifth and sixth will exhaust her lines.
(Optional) Speak to Thiollier:

Interaction: If Thiollier is present, you can attempt to relay St. Trina’s words to him. Thiollier will react negatively, calling you a liar, and may threaten you upon further attempts. Defeating Thiollier after resting at a nearby Site of Grace will reward you with the St. Trina’s Smile Talisman.
Return to the Garden of Deep Purple:

After Final Boss: Post-boss fight, revisit the Garden of Deep Purple. You’ll find St. Trina’s body there, allowing you to elden ring items buy collect St. Trina’s Blossom.