Defeat Kahmunrah for this achievement. To do this, you'll need to deactivate 3 obelisks whilst avoiding his projectiles and the slow moving fireballs from the 2 anubis guys. If you get hit, there's a energy scarab that respawns for you regularly.

Use your keychain (LT) on the front of the 1st obelisk and then hide around the back. Use your Gear power to rotate the 3 sections to match up (from memory I think I moved the middle section once then the bottom section twice). You'll get a cut scene before you can move on the the 2nd obelisk.

Use your keychain again at the front to activate it. This obelisk has 4 pictures, one on each side, of a seed, sprouting, grown and then flowering plant. Use your Paintbrush power on each side, starting with the seed at the front and then in the order listed which will move you around the obelisk anti-clockwise. Each image will glow white if you're doing it right. Another cut scene will follow.

Keychain the front of the 3rd obelisk and get your Animal power ready. There are 2 beetles and 2 gems on each side and you must rotate each beetle to face a gem of the same colour, whether it is above, below or on another side to the left or right. Take your time to avoid the attacks from the bad guys and you'll soon finish this task.

After the next cut scene, run up to Kahmunrah and use your keychain to take the Tablet from him and finish the game.