Mad Santa is another one of the various Santa Claus references
Server Heart’s sprite refers to the popular “potato servers” trope, implying servers are so bad they might be powered by potatoes.
Weapons that drop from The Machine are references to some UGC members.
Refer to their Realmeye pages:
Blade of Ages’ refers to @Xaklor
Butter Bow refers to @Toastrz
Caduceus of Current Craziness refers to @Atrapper
K.I.D.D. Force refers to @Kiddforce and also versions of the Lost Halls dungeon
MMace MMurderer refers to @MMoas
Mister Mango refers to a sprite made by @Mrunibro (this one was already spotted in this thread, but I’ll include it for completion
Null refers to Nullbot, the only dev that worked on RotMG late in Kabam era
Futuristic Cloth’s 0s and 1s green on black pattern refers to the stereotypical hacker screen in pop culture and movies.