All or Nothing

You will begin at Hoover Dam amidst a fierce battle between the Legion and the NCR. If you have a good reputation with the NCR, they will not attack you and can serve as allies against the Legion. If your reputation is poor with both factions, you will have to contend with both NCR Rangers and Troopers. It is advisable to use stealth, let the factions fight each other, and pick off the survivors.

Your objective is to travel north-east across the top of the dam, past the Visitor’s Center. A turret will explode as you proceed. If you convinced the Khans to perform a suicide attack, they will appear here and perish. If you did not break the alliance with the Khans, they will be fighting for Caesar’s Legion and you will need to eliminate them. Continue north-east, engaging any Legion or NCR forces, and utilize Securitrons and the NCR for cover (press the cover button to crouch behind walls or objects) when possible.

As you approach the center of the dam, you will find an inaccessible checkpoint (an auto-save point you restart from on death). If you enlisted the Boomers' aid, they will bomb combatants on the far side of the dam. Turn south-east and enter a Hoover Dam Tower, then take an elevator down to the Hoover Dam Offices.

The Hoover Dam Offices contain similar threats, with NCR Troopers sometimes engaging Legion infiltrators. Proceed through a door to the south into a hallway. Follow it east, then south, and take the first east turn to find two NCR Heavy Troopers in Power Armor wielding Heavy Incinerators. If they are hostile, defeat them. If not, pass a [Speech 75] check to persuade them to leave.

Enter the room they were guarding and examine the terminals. Install the Override Chip onto the mainframe. Mr. House will then take control of the situation.

Proceed to the eastern generator and flip a switch to activate the Securitron army against Caesar’s Legion. You will also find the note “Order of Withdrawal” detailing the NCR’s surrender terms.

Exit the control room and find a door leading to the Hoover Dam Power Plant on the eastern side of the Offices level. Turn west to find the East Power Electrical Switch on the wall. Activate it to initiate the final phase of Mr. House’s plan.

Return to the Hoover Dam Offices area and find a door to another Hoover Dam Tower on the eastern side of the level. Ascend to the eastern end of the dam.

Once back outside, follow the dam south-east. Observe Mr. House’s Securitrons engaging Caesar’s Legion. If you completed the quest _For Auld Lang Syne_ and directed the Khans against the Legion, they will assist you. Securitrons will also bolster your ranks at the end of the dam. Where the road ends, turn east and cross a ruined bridge to reach The Legate’s Camp.

Enter the camp and head east to a fortified area occupied by Praetorians. Engage them from a distance to avoid their Ballistic Fists. Continue east through the camp.

At the eastern end, ascend stairs to find Legate Lanius. You can choose to fight him directly. He is accompanied by Praetorians. If you have strong weapons and use consumables like Med-X and Psycho, he can be defeated. Upon being injured, he will flee towards the west of the camp, throwing Frag Grenades, and use Legendary Healing Powder to recover before re-engaging. You can loot him for his Legate Helmet and Blade of the East.

Alternatively, you can attempt diplomacy. Select the dialogue option “Maybe you’re willing to listen to reason.” You will then face a series of Speech checks: [Speech 55], [Speech 65], [Speech 75], [Speech 85], and three [Speech 100] checks to convince Lanius that the Legion cannot sustain attacks on both the east and west.

You can also attempt another series of Speech checks: [Speech 60], [Speech 75], and two [Speech 90] checks. After the second [Speech 90] check, continue talking to Lanius and you will have a [Speech 80] check to convince him to fight you one-on-one, removing his Praetorian backup.

If your Barter skill is higher than your Speech skill, you can use those checks instead.