Story to Unlock Gostoc Merchant in Roundtable Hold – Elden Ring
First, you have to find 5 graces outside of dungeons.
Melina will appear and talk to you.
You need to go with Melina to a roundtable hold.
You can only find five graces (outside the dungeon).
After that, meet Gideon Ofnir (leader of this place).
And then meet Corhyn.
The two fingers door is locked.
You will need to go to the stormveil main gate grace.
And talk to gatekeeper Gostoc.
Gostoc steals runes from you.
If you die, he steals from runes drop.
You have to kill him to get runes back (but wait).
After that, go to secluded cell grace.
And enter mist to battle Godrick the grafted.
1st godrick cutscene starts.
2nd Godrick cutscene starts at half HP.
You will need to kill Godrick.
After that, touch Godrick the grafted grace.
Fast travel out to any grace then fast travel back to Godrick the grafted grace.
Gostoc will be stomping on Godrick's head.
You have to talk to Gostoc.
And kill Gostoc (after beating godrick).
Only 200 runes if you kill him here.
Get gostoc's bell bearings.
Fast travel to roundtable hold.
Go to twin maiden husks.
Talk and offer a bell bearing.
Offer Gostoc's bell bearing.
After that, you have to examine Gostoc's merchant shop.