They are not named after a World of Warcraft character and their 4th album cover has nothing to do with Adventure Time.
These are photos from concerts where Lich King played, so they may be of other bands that played the concert as well.
Lich King / Malignancy / Narcotic Wasteland / Scattered Remnants / Belushi Speed Ball / Bonginator / Deterioration / Maul / Concrete Caveman / Mutilation Barbecue / Left to Rot / Field Dressed / Anti-Sapien / Black Mass / Chained To The Bottom Of ... Jun 28 - 30, 2024 Litchfield, New Hampshire, United States Uploaded by Bigtravsburnerphone
70,000 Tons of Metal (Thursday) Feb 1, 2024 Miami, Florida, United States Uploaded by Trey Smith
70,000 Tons of Metal (Tuesday) Jan 30, 2024 Miami, Florida, United States Uploaded by Trey Smith
Lich King / Exmortus Aug 16, 2021 Las Vegas, Nevada, United States Uploaded by Vegas Berzerker
Maryland Deathfest 2019 May 23 - 26, 2019 Baltimore, Maryland, United States Uploaded by Clay
SWR Barroselas Metalfest XX 2017 Apr 27 - 30, 2017 Barroselas, Viana do Castelo, Portugal Uploaded by La666