The Grand Obelisk is the third and final level of The Legend of the Beast DLC.
Sam has finally reached the Great Obelisk, but the door that leads to the sacrificial chamber is locked. Sam heads to the back of the Great Obelisk and finds a key, then returns to the front while under heavy fire by Mental's forces. After going through one more wave of enemies, Sam finally manged to get inside the Great Obelisk, but finds a large hole in the floor that leads to the sacrificial pit.
After falling down for a bit, Sam finds himself in a blood-soaked room with a Khnum on a throne, which is wearing the Sign of Amon-Ra that Sam needs. Thanks to a conveniently-placed trap, Sam manages to kill the Khnum, retrieve the Sign of Amon-Ra from its neck, then start his journey to Karnak.
- At the back of the Obelisk, there is a building with a sphinx statue on it. Jump on a nearby torch, then jump onto the building. On the front of the sphinx is a small switch. Use the switch, and the building will move backwards, revealing a hidden room that has a Large Armor and two bullet boxes. Simply hitting the switch will register the secret.
- Go to the area that has the XPML21 Rocket Launcher. From there, look for a room that's located on the upper right side of the Rocket Launcher area. Inside that room, there is a switch behind the north-most torch. Use it, and a part of the roof will come down. Jump on the elevator, and the player will be lifted to a room that has ammo and health. Getting to the secret room will register the secret.
- After picking up the rocket launcher, go back to the door that was used to enter the area behind the Great Obelisk. Now, look at the part of the Obelisk that's to the right of the door. You'll find a Super Health on a piece of the wall that is jutting out. Shoot a rocket at the wall, and the Super Health will fall down, which will register the secret.
- After going doing a complete run through the Great Obelisk's perimeter, go back to the first doors you went through, then go through them again. When you do, a Super Armor and Super Health will spawn just past the doors and a secret will register. Make sure to pick these items up quickly and go through the doors again, or else the doors will close and you'll have to walk around the Obelisk's perimeter again.
Note that this secret can be picked up when you first open those doors up. Open the doors up, back out, then go through them again. This will make the items appear and will register the secret. This is much more useful, as the extra armor and health will be needed when going through the Obelisk's perimeter.
- This level was supposed to be the third level for Serious Sam: The First Encounter at one point. It's internal name matches the third level found in a co-op level list in Test 1's files.
- A glitch can occur after the death of the boss in which you spawn in one of the cinematic areas, the dark corridor of which Sam is walking in. You appear behind him, and he moves on the spot, then the cinematic loads as normal.