Final Fantasy 11: King Behemoth

While I was in Behemoth's Dominion, I got to see someone spawn and fight King Behemoth.

https://ffxiclopedia.fandom.com/wiki/King_Behemoth

Get the game on Steam: https://store.steampowered.com/app/230330/FINAL_FANTASY_XI_Ultimate_Collection_Seekers_Edition/

I recommend playing the game with a free launcher called Windower: https://www.windower.net/

I used this online guide to complete missions & quests:
https://ffxiclopedia.fandom.com/wiki/Main_Page