Halo Infinite – LASO Guide (How to Get Headmaster Achievement)

This is LASO guide for getting Headmaster achievement in Halo Infinite.

LASO Guide

How to Get Headmaster Achievement


Note: before attempting LASO you will need to have collected all twelve skulls on a previous game.

If you are new to LASO (Legendary All Skulls On) it was originally created by fans who wanted a greater challenge than just playing on Legendary difficulty. The accomplishment gained in popularity and now is supported through official playlists found in Halo: The Master Chief Collection (MCC) and achievements in MCC and Infinite.

Infinite’s LASO difficulty is very easy when compared to the other games because of the new armor abilities, open world map, lack of an Iron Skull (resets current mission/checkpoint on death), Bandana Skull requirement (unlimitted ammo, grenades, no ability cooldowns), and most importantly the secret Scorpion Gun.

While this may be disappointing to fellow LASO Masters, it is still fun and does provide a good starting point for those who are new to the challenge.

Key Details

Checkpoints are only triggered when the player has full shields. The best tactic is to kill all the dangerous enemies while saving one Grunt or Jackal last to melee for the shield recharge. Remember that checkpoints will be invisible because of the disabled HUD but are usually pretty frequent. This is very important because a lot of progress can be lost otherwise.

The Scorpion Gun can only be acquired during the Outpost Tremonius mission (instructions below). If you plan to use it on your LASO run then make sure to obtain it before entering the Pelican on the landing platform otherwise the mission will end and it will become unavailable for the rest of the game.

If using the Scorpion Gun it is imperative that you never drop it as doing so will cause the weapon to immediately despawn and it cannot be reacquired if permanently lost. Be cautious when interacting with mission consoles and using the Grappleshot because it’s very easy to pick up another weapon. If you do accidentally drop it you can either quickly kill your spartan to reset the checkpoint, manually end game and reload to the prior checkpoint, or restart the current mission from the beginning.

When returning to your LASO campaign, be sure to use the manual “Load” option versus choosing to “Continue.” Some players have experienced the skulls becoming disabled when choosing continue which could potentially affect the achievement.


Here are all twelve skulls for Halo Infinite and their game affects:

  • Black Eye – Shields only recharge when you melee enemies.
  • Catch – Enemies throw and drop more grenades.
  • Fog – Disables motion tracker.
  • Famine – Weapons dropped by enemies only have half ammo (mitigated by Bandana).
  • Thunderstorm – Upgrades the rank of most enemies.
  • Mythic – Enemies have increased health.
  • Blind – HUD and weapon do not display on screen.
  • Boom – Doubles explosion radius.
  • Cowbell – Accelerations from explosions increased.
  • Grunt Birthday Party – Grunt headshots lead to glorious celebrations.
  • IWHBYD – Rare combat dialog becomes more common.
  • Bandana – Unlimited weapon ammo, grenades, no ability cooldown.


To start your LASO run begin a new campaign with the difficulty set to Legendary and ALL twelve skulls enabled, yes even Bandana! The first three missions are the hardest but once you make it to Outpost Tremonius and obtain the Scorpion Gun things become significantly easier. Until then you can use a Plasma Pistol to bring down enemy shields and then use a precision weapon to headshot them.

The Blind Skull disables the HUD so make sure you are familiar with the missions. The AI Scan feature still works and will reveal the items that need to be interacted with to progress. The TACMAP can, of course, still be used and waypoints set on it will show the pillar of light in the distance (but no icon) for open world navigation. If aiming is too difficult check your monitor for a built in reticle that can be turned on or use a tiny piece of painter’s tape. Additionally, you should also be familiar with the controller button combos that select the different grenades and armor abilities.


  • Fragmentation: Left, Left
  • Plasma: Left, Up
  • Spike: Left, Down
  • Dynamo: Left, Right


  • Grappleshot: Right, Right
  • Thruster: Right, Up
  • Threat Sensor: Right, Down
  • Drop Wall: Right, Left

Regarding grenades, I recommend Dynamo which is basically all I used on my run. They provide a short AOE stun (along with damage) to enemies which can be used to escape in a pinch or line up a shot without taking damage. These affect the bosses too.

The armor abilities greatly benefit from the Bandana Skull which cause them to have no cooldown. The mainstays will be the Grappleshot and Threat Sensor. Scaling sheer cliffs is a breeze and spamming the sensor will help to locate and target enemies from a safe distance or move in for that sweet shield recharge melee.

It should be noted that when using the Scorpion Gun the Drop Wall cannot be deployed (but can if you swap to your backup weapon). It is also impossible to melee with the Scorpion Gun. Thrusters are mostly useless as even with the final upgrade that provides temporary cloaking enemies will still (somehow) be able to see you.

There is no splash damage to the player from the Scorpion Gun so you can fire point blank if needed. However, if there are fusion coils in range you risk causing those to explode and damage your shields. You can have a secondary weapon along with the Scorpion Gun and it’s really based on personal preference. I liked the Pulse Carbine because it fired quickly (causing some enemies to flinch) and allowed me to take down the shields on Grunts and Sentinels (the latter often at range) and move in for the kill with a melee shield recharge.

Lastly, you’ll come across some Spartan Cores while playing and I highly recommend upgrading Shield Core and Threat Sensor to max and placing at least one core into Grappleshot for the stun. It’s entirely optional if you want to capture any FOBs to reveal additional Spartan Cores for further upgrades (I did on my run) and for quicker travel around the map. The basic abilities with no upgrades are more than sufficient.

Keep in mind though that between the Cowbell and Boom Skulls and the Scorpion Gun enemies are liable to go flying off into space and sometimes this prevents the trigger for all enemies being defeated and thus the FOB cannot be claimed (I encountered this several times). In that case simply Fast Travel to another FOB to reset the area and then go back and try again.

Scorpion Gun (Secret)

The secret Scorpion Gun is very easy to obtain but as previously noted it must be done during the Outpost Tremonius mission and before boarding the Pelican. You can return to the outpost later but the button will no longer be present. It is highly useful for a LASO run.

At the end of the mission there will be a large courtyard with buildings, a crashed ship, and landing pad. Use the Grappleshot to scale up the side of the ship to the two turrets.

Once atop the ship proceed to the rightmost turret and you’ll see a fallen marine and red datapad. Interact with the datapad until it powers down.

Next, proceed to the other turret.

Jump up onto the rightmost barrel, walk to the end, and look down at the tip of it. Hold down the action button until you drop your current weapon. Find a target and fire!

by N7 Spectre

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One comment

  1. One thing about LASO in Halo Infinite that wasn’t true in some of the other games…..
    Your Sword Melee DOES recharge your shield! And also, your shield recharges not only on enemy death. So you can keep bashing somebody to get recharges.
    This helps quite a bit during the Tremonius fight! If it weren’t for those 2 jackals, you’d probably be able to kill him on the first or second try by simply repeatedly Grappling to him and Sword-meleeing and repeating over and over. If you Grapple him fast enough at the start, he wont be able to ground-pound you. You’ll have to go over and get some shield by meleeing the jackals after, but once they are out of the way, you’ll see he’s not that bad if you brought a sword.

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