Made an updated guide since the owner of the original guide hasn't updated his.
Defeat boss in temple area. (Exclusive to AOTI)
Go to Neudaiz and either go through the Pavilion of Air missions to get to the Top floor of it or have a friend special flight you there. Bring a gun just in case this monster goes airborne. (Weak to Light
De Rol Le Slayer40
Defeat boss in cave area. (Exclusive to AOTI)
Go to Moatoob and take the special flight to N. Cont. Granings ~ Voloyal Area or go through the following missions :System Defense -> Desert Tear-> Tunnel Recapture -> Caves of Ice. Bring a gun just in case you need it.(Weak to Fire
Mother Brain Slayer50
Defeat boss in relics area. (Exclusive to AOTI)
Go to Parum and either special flight to Paracabarna Coast Area or take the following missions: AMF HQ Recovery -> Millitary Subway -> Electronic Brain. (Weak to Ground)
Dark Falz Slayer60
Dark Falz defeated.
Go to the Guardian's Colony 4th Floor and take the HIVE missions to the end. The name of the mission containing Dark Falz is "The Dark God".(Weak to Light
Dark Falz 2 Slayer 60
Defeat boss in dark area.
Not Yet Available. Maybe available on Friday with the Shred the Darkness event.