The Void based champions in LoL reference or parody Lovecraftian horrors, Kassadin seems to reference Call of Cthulu especially, some links to their lore for reference:
Kassadin's: http://na.leagueoflegends.com/champions/38/kassadin_the_void_walker
Cho'Gath's: http://na.leagueoflegends.com/champions/31/cho_gath_the_terror_of_the_void
Kog'Maw's : http://na.leagueoflegends.com/champions/96/kog_maw_the_mouth_of_the_abyss
Malzahar's: http://na.leagueoflegends.com/champions/90/malzahar_the_prophet_of_the_void
Mordekaiser could also work: http://na.leagueoflegends.com/champions/82/mordekaiser_the_master_of_metal
However, Eternal Darkness really is the most Lovecraftian game I've seen. The monsters look otherworldly and literally drain your insanity on sight, weird insanity effects play throughout just to mess with you, and most of the characters end up with very bad ends.
Kassadin's: http://na.leagueoflegends.com/champions/38/kassadin_the_void_walker
Cho'Gath's: http://na.leagueoflegends.com/champions/31/cho_gath_the_terror_of_the_void
Kog'Maw's : http://na.leagueoflegends.com/champions/96/kog_maw_the_mouth_of_the_abyss
Malzahar's: http://na.leagueoflegends.com/champions/90/malzahar_the_prophet_of_the_void
Mordekaiser could also work: http://na.leagueoflegends.com/champions/82/mordekaiser_the_master_of_metal
However, Eternal Darkness really is the most Lovecraftian game I've seen. The monsters look otherworldly and literally drain your insanity on sight, weird insanity effects play throughout just to mess with you, and most of the characters end up with very bad ends.