Crown of the Sunken King Rings | Dark Souls 2 Wiki

0.2

• Grants the user bonus physical attack based on
  their maximum equip load (Vitality) stat. Lower stat, better bonus

• Can be found in an iron chest in Dragon's Sanctum after falling through the gap in the stairs and then taking a left, dropping down into the room with the Corrosive Egg Crawlers then going up a ladder.

0.5

• Has a chance to prevent any damage from spells that hit you.

• After the final boss fight. You find it on a corpse near to the portal, where you get the crown.

2.0

• Grants the user bonus lightning damage and reduces the player's
  physical defense by 80 points.
• The ring seems to add a bonus of +30 AR to
  the lightning damage on weapons.

• After entering the Dragon's Sanctum there is a closed door on the left side, use the Eternal Sanctum Key to open it. Inside there are 2 Sanctum Priestess and 5 chests. The ring is inside the 2nd chest from the left.

1.0

• Increases lightning defense by 150

• Near the second bonfire in Shulva, on a corpse in one of the moving pillars that you use to get to the second bonfire. In the second closest pillar to the bonfire. On the higher ledge of the pillar, the ledge under it has a corpse with two Darknight Stones.

1.0

• Increases dark defense by 150

• Loot from a body on top of a platform in the first area of Shulva - Sanctum City

1.5

• Increases Poison Resistance by 300

• At the first bonfire in Shulva - Sanctum City, after the first Sanctum Knight that is sitting down, look left and shoot the obelisk switch on a small piece of land across the gap. This raises a platform you drop onto. Once on the platform, go through the door on the left, and go up the stairs. You can find the Ring on the corpse on the top of the tower.

1.5

• Increases Bleed Resistance by 300

• In Dragon's Sanctum, in a metal chest next to a walkway in the room with floors covered with spikes.