The battle between the Dragon Boat and the Vengeance in Magykobviously fits.
Septimus casting the projection spell in Queste to divert the Guards of the House Of Foryx from Nicko.
The fight between Septimus and Merrin in Darke.
In Darke, Beetle risks his life to protect the Maniscriptorium and manages to survive a good 24 hours in a small, airtight room without the charm that was supposed to help him by doing ancient breathing excercises. He was chosen as Chief Hermetic Scribe for a reason, folks.