Vous ne pouvez recevoir qu'un Drop de la part d'un Boss ou d'une FOE à moins que vous n'utilisiez du Formaldehyde le Tour que vous ACHEVEZ le Boss.

Forest Frog – Frog Fluid: kill with bash damage
Mandrake – Sealed Neck: kill while head is bound
Ghost Owl – Shocked Talon: kill with lightning
Lynx - Sealed Claw: kill while arms are bound
Petaloid – Dangerous Bud: kill with instant death
Hollow Believer – Panic Chakra: kill while confused
Claw Beetle – Broken Horn: kill with bash damage
Maya Owl – Sealed Skull: kill while head is bound
Magma Spawn – Scorch Stone: kill with an attack that is not Fire, Ice, or Lightning
Glacier Spawn – Frigid Stone: kill with an attack that is not Fire, Ice, or Lightning
Baboon – Toxic Bone: kill while poisoned
Flame Rat – Flame Tail: kill with slash damage, low probability
Medusa Tree – Scorched Sap: kill with fire
Purple Anoir – Stunned Tongue: kill while paralyzed, low probability
Cursed Shroom – Sealed Cap: kill while head is bound
Dragonfly – Shocked Bug Eye: kill with lightning
Magma Beast – Magma Core: kill with an attack that is not Fire, Ice, or Lightning
Glacier Beast – Glacier Core: kill with an attack that is not Fire, Ice, or Lightning
Ice Bulb – Icy Seed: kill with petrification
Wrath Bloom – Scorched Petal: kill with fire
Hollow Magus – Frozen Heart: kill with ice, low probability
Muskoid – Deathly Bud: kill with instant death
Red Lion – Red Lion Fang: low probability

FOES
Nightmare Ram – Toxic Eye: kill with poison damage
Trigourd – Pumpkin Head: low probability
Hexgourd – Pale Bone: low probability
Flygourd – Cursed Vine: low probability
Moth Lord – Eerie Scales: low probability

Overworld FOES
Raging Raptor – Raptor Claw: kill while legs are bound
Death Mantis – Stony Scythe: kill with petrification

Boss
Berserker King – Berserker Skin: kill in one turn
Hollow Queen – Cursed Eye: kill with curse damage
Boiling Lizard – Effulgent Horn: kill with fire
Cradle Guardian – Dream Carapace: kill while Asleep (Le Boss lui-même, la tête n'a pas de conditionnel)

Quest Boss
Baboon King - Kingly Skin: kill while confused
Chameleon King – Colorful Tongue: kill with ice
Hraesvelgr – Raptor Talon: low probability
Sand Leviathan – Poison Wing: kill while poisoned
Blizzard King – Frozen Skin: kill with ice
Storm Emperor – Charged Horn: kill with lightning
Great Dragon – Fire Fang: kill with fire
Iwaoropenelep – Chaos Feather: kill while confused
Fallen One – Sealed Core: kill while head is bound

Source:
http://www.gamefaqs.com/boards/997793-etrian-odyssey-iv-legends-of-the-titan/65640517

Très utile, merci beaucoup !

Petite question : il me semble que dans les autres EO, on pouvait refaire les boss en laissant passer un certain nombre de jours, c'est la même chose dans celui-ci ? Si oui, combien de temps faut-il attendre ?

Tous les 14 Jours les Boss & Boss de Quêtes réapparaissent.
Sinon se serait impossible d'avoir tous les Drop des Boss et Boss de Quêtes

Ok, merci Roi-Niark !