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The Elder Scrolls IV: Oblivion Walkthrough The Great Gate
The Elder Scrolls IV: Oblivion The Great Gate
Martin will have you talk to the Countess to supply a militia, then you must defend him outside Bruma.
If Martin dies here, you'll immediately reload the last save. Ensure he lives whilst more Gates open. You can't close these gates, so just hack+slash.
If all three open without Martin dying, a HUMONGOUS gate will open. This is the one you must enter.
Don't worry about Martin anymore! The battle outside is paused, you have fifteen real-time minutes of getting to the central tower and taking the Sigil Stone before the gigantic fireball-of-death breathing machine kills everybody outside.
It doesn't matter where you go to get to the central tower, only that you get there.
Head into the supplementary towers and open lifts and press buttons to open gates that'll let you forward.
Beware the fireballs of death.
To get into the central tower, head into the supplementary towers and press any buttons you can find, then head back.
Once the gates are open, head into the central tower and slaughter your way up, taking the Sigil Stone and ending the siege.
Back at the Temple, Martin will open a portal to Camoran where you can kill him.