Northern Shaft Key
From WikiRaider
Northern Shaft Key is a key found in the level The Mastabas in The Last Revelation. It's used in the level Inside the Great Pyramid alongside with three other shaft keys.
It's important not to leave the level The Mastabas before both the Northern Shaft Key and Southern Shaft Key are found, since after proceeding into the level The Great Pyramid, it's not possible to re-visit the level. Having all four shaft keys opens the exit in Inside the Great Pyramid. Not having all of the keys won't be a problem if one uses the level skip cheat, but doing so may cause some problems (see The Last Revelation Cheats for further details).