The Evidence reveals that the Master Chief is in Danger, the Fireteam travels to Elite's home in order to rescue the Blue Team and gain the Arbiter's support. Let's check out how the Fireteam manages to rescue Blue team in Mission 8: Swords of Sanghelios.
After the cutscene concludes, you'll take over the Locke along with Fireteam at Sanghelios. Listen to the information carefully from Mahkee 'Chava, he will guide you on where to find the Arbiter, but as you reach you notice a civil war is broken out and you need to take care of Elder Council Chambers.
Keep Following the water which will lead you to a canyon. Deal with few of the enemies ahead and make sure to pick up the D-pad from the left-hand side of the Statue. Use the D-pad to keep a check on you movement and keep moving and climbing up until you face some more Jackals and Covenant along with the suicide bombers off course.
Once Eliminating the enemies you need to climb up the Ruins of Sangheli. The waves of enemies are endless so just keep moving and take the enemies which are on your way rest ignore or if you like to play some more then just go with it and clear it all. As you enter the Ruins you'll come across the Hornet's Nest, move forward and secure the Landing zone from the soldiers.
Few hunters will also join you at he Landing zone so make sure you have enough ammo. Keep a check on the team's health as well if they require any assistance. After finishing them, all few allied forces will join us and help us out. Quickly mount up on the Mantis and as the gate will open lets role with our new Armor. There are a bunch of enemies waiting for us on the other side but with Mantis it can be done with ease.
Head towards the Elder Council Chambers after eliminating the enemies. Keep following the Allied forces far side of the courtyard where you'll locate the Elder Council Chambers. Head straight locate the Arbiter as fast as you can as the Arbiter's forces are losing the fight. Climb the Staircase and extract the Arbiter with the help of Mahkee 'Chava and the cutscene will begin. End of Mission 8: Swords of Sanghelios.