Monster Sanctuary: Material Drops Guide (Where to Farm Them Efficiently)

• Blob
  
• Magmapillar
  
• Frosty
  

Iron

• Blade Widow
  
• Imori (this entire room is good 2 Blade Widow on the bottom and Imori)
  

Bronze

• Aurumtail
  

Iron and Bronze

• G’rulu (Two for the price of one!)
  
• Druid Oak
  

Steel (Earlier)

• Ucan x2 and Vaero/Dodo x2 and Ucan
  
• Goblin Miner x2 and Salahammer
  

Steel (Later)

• Promethean
  
• Mega Rock
  
• Darnation
  

Silver (Earlier)

• Nautilid
  
• Gobin Miner x2 and Glowdra
  

Silver (Later)

• Argiope x2 and Giant Rock (all weak to fire)
  
• Stolby
  

Gold

• Mimic (2 rooms)
  
• Oculus x2 and Ornithopter
  

• Manticorb (requires double jump)
  
• Yowie
  

Wool

• Mad Eye
  
• Toxiquus
  
• Mogwai
  

Leather

• Aurumtail
  
• Ninki Nanka
  

Raw Hide (same room)

• Ucan x2 and Vaera with Dodo x2 Ucan
  

Silk (Earlier)

• Draconov x2 and Glowdra
  
• Silvaero 2x and Vaero
  

Silk (Earlier)

• Argiope x2 and Arachlich
  

Linen

• Mimic (2 rooms)
  
  
• Stolby
  
• Ornithopter
  

• Manticorb (double jump)
  
• Vaero
  
• Toxiquus
  

Green Gem

• Blob
  
• Crackle Knight x2 and Grummy
  

Blue Gem

• Magmapillar
  
• Yowie
  
• Manticorb
  

Crimson Gem

• Blade Widow
  
• Imori
  
• Lava Blob
  

Verdant Gem

• Goblin Miner x2 and Salahammer
  
• Megataur x2 and Crystal Snail
  
• Ucan x2 and Vaera with Dodo x2 Ucan
  

Azura Gem

• Aurumtail
  
• Vasuki x2 and Ninki Nanka
  
• Nautilid
  

Ruby

• Ornithopter
  
• Promethean
  
• Worm x6
  

Emerald

• Mega Rock
  
• Stolby
  
• Oculus
  

Sapphire

• Argiope x2 and Giant Rock (all weak to fire)
  
• Polterofen x2 and Steam Golem
  
• Changeling
  

Thanks to KKP2112 for his great guide on how to farm material efficiently, all credit to his effort. you can also read the original guide from Steam Community. enjoy the game.