Weirdest ones:

• The highest mastery Gnar runs Ignite TP and goes full damage with Shieldbow/Wits End/Botrk/Rage Blade
  
• Graves runs Smite Ignite and has been going Prowers BT into FULL TANK
  
• Janna plays Janna jungle, actually jungle not top with smite, and goes full crit ADC builds.
• Jayce never builds Muramana, and he goes first item GA into second item Serylda's Grudge
  
• Kog'Maw runs TP Ghost, usually plays mid but plays an unsettling amount of support Kog'Maw.
  
• Malphite runs TP Heal and plays support
• Elise plays top lane with Ignite Flash or Barrier Flash. Builds are all over the place. AP, AD, Hybrid, Tank, there are no rules
  
• Heimerdinger runs TP Heal, thinks he has Cassiopeia passive. At least as far as I scrolled he has never bought boots
  
• Akshan runs TP Heal, plays it bot lane
  
• Mundo is another TP Heal fan
  
• Ashe runs Heal Ghost, rushes BT mythic seems to usually be 3rd or 4th item.
• Caitlynn runs TP Heal and GLACIAL AUGMENT
  
• Neeko runs Ignite Ghost, build is Crown>Void>Nashors
  
• Pantheon heckin loves Serylda's Grudge, usually builds it first item
  
• Rammus builds Berserker Greaves every game also takes grasp fairly often
  
• Rek'Sai collector first item, then eclipse
  
• Rumble is a rumble support player. He takes TP, and he often sells his support item
  
• Sivir runs Heal Ghost, builds BT>IE before a mythic every game
  
• Tristana runs with TP Ghost and Electrocute
  
• Volibear runs Barrier Ignite top lane, builds a mix of AP/AD/Tank
• Wukong plays mostly support
  
• Xin Zhao rocks Smite Ignite and likes to rush BT
  
• Yumi, #1 mastery doesn't have any recent games, #2 mastery runes Heal Ghost and builds mobi boots.
  
• Zoe was experimenting with Grasp Full Tank Zoe today, but appears to usually have a pretty standard build

Honorable mentions (not ridiculous, but different):

• Jhin's build is pretty normal but his name is JhinTopNoTroll and you guessed it, he plays Jhin top.
  
• Karma plays support, and goes Flash Ghost and Liandries every game.
  
• LeBlanc confuses me because their OP.GG looks like they've turned into a Garen 1 trick.
  
• Lee Sin appears to have stopped playing.
  
• Lissandra same decent (but suboptimal) build EVERY. SINGLE. GAME. Liandries>Zhonya's>Morello>Banshees.
  
• Lilia runs Ignite Exhaust and plays Mid/Top, only jungles on rare occasion.
  
• Lucian is a homie in ARAMs, runs Clarity Heal.
  
• Lulu generally runs lethal tempo and full AP with Nashors Lich
  
• Nasus runs Heal Ghost, but he has spellbook so it's less weird (assuming he actually uses it)
• Nidalee is a bruiser top nidalee player, and is Master Tier
  
• Nocturne top with Ignite Ghost build is mostly reasonable but really likes thornmail
  
• Nunu, it's nunu top.
  
• Poppy mid/top with ignite, dark harvest, and full damage/lethality builds
  
• Sion is AD Sion Jungle
  
• Twisted Fate plays AD TF every game
  
• Vel'Koz appears to queue primarily for top lane
• Vayne is another Heal Ghost fan
  
• Vi usually building Kraken Slayer or Shieldbow