Ninja Gaiden Sigma Plus

Missable!
There are a total of 13 ambushes, 10 for Ryu and 3 for Rachel. You must be aware of the conditions for each ambush to occur or you won't be able to trigger all ambushes. Some ambushes occur after a specific chapter is completed. Certain ambushes won't trigger if you've completed a chapter or destroyed a boss or triggered another event. Below are the list of each ambush in order.

• Ryu Chapter 3 - Airship (Need ID Card)
• Ryu Chapter 7 - Archives Room (If you defeat Alma, this won't trigger)
• Ryu Chapter 10 - Ritual Room (Available after Alma is defeated)
• Ryu Chapter 12 - Peristyle Passage (long and huge hallway *cannot be missed*)
• Ryu Chapter 12 - Aqueducts 4B (Bugs spawns, good essence farming place)
• Ryu Chapter 15 - Zarkhan Stadium (After Doku is defeated and you activate switch)
• Ryu Chapter 16 - Underground Passage (Cannot be missed)
• Ryu Chapter 16 - DrawBridge Square (Cannot be missed)
• Ryu Chapter 18 - Great Bridge Square (Must travel back to the city)
• Rachel Chapter 5 - Monastery Annex (Back area behind Monastery *Hard to find*)
• Rachel Chapter 8 - Military Gate (Don't fight Gamov or you'll lose this chance)
• Rachel Chapter 14 - Hayabusa Village (Near Save and Muramasa's statue)