Elden Ring PC | Morgott, The Omen King boss fight co-op w/2 summoned players on NG w/achievement

The amount of runes that drop from a boss is less when you have summoned players to help and can also change if you're wearing the Golden Scarab talisman, which adds a 20% bonus to runes gathered from enemies.

Drops:
108,000 runes
Morgott's Great Rune
Remembrance of the Omen King
Sharbearer Morgott achievement (Steam / PC)

Morgott, The Omen King
"Morgott, The Omen King, also known as Morgott the Grace Given, is a Demigod Boss in Elden Ring. Morgott is the true identity of Margit, the Fell Omen, and the self-proclaimed "Last of All Kings". Although he and his twin brother Mohg were imprisoned deep in the Subterranean Shunning-Grounds for being born as Omen royalty, Morgott still loved the Golden Order and defended the capital when his fellow demigods invaded during the Shattering. This is not an optional boss as players must defeat him to advance in Elden Ring."
https://eldenring.wiki.fextralife.com/Morgott+the+Omen+King

Morgott's Great Rune
"Morgott's Great Rune is a Great Rune in Elden Ring. Morgott's Great Rune raises maximum HP. Great Runes in Elden Ring are special items dropped by Demigod Bosses that can be equipped to acquire special passive bonuses."
https://eldenring.wiki.fextralife.com/Morgott's+Great+Rune

Remembrance of the Omen King
"Remembrance of the Omen King is a Consumable Item in Elden Ring. Most Consumables grant various effects such as restorative properties for recovering HP, removing certain negative status effects or applying temporary buffs and debuffs, while others can be thrown at enemies to deal damage."
https://eldenring.wiki.fextralife.com/Remembrance+of+the+Omen+King

Shardbearer Margott achievement
https://www.trueachievements.com/a354488/shardbearer-morgott-achievement