The MYTHIC achievement in Halo: Campaign Evolved asks you to finish the whole campaign on Legendary with all 17 LASO skulls active, and the game tells you plainly that custom difficulty modifiers will block that reward. In practice the modifiers make missions much easier while your LASO completion still ticks up, and a quick checkpoint trick pushes that progress into the achievement tracker.
Quick answer: Build a modifier preset at Damage Resistance 2000%, Shield Recharge Rate 200%, Damage Modifier 300%, Melee Damage Modifier 300%, and Bottomless Clip ammo. Clear a mission on the Play LASO playlist with that preset on, switch the preset to None, load The Pillar of Autumn on LASO, grab the Speed Limit skull in the first room, wait for the checkpoint, then quit. Repeat for all 13 missions.
Why the modifiers do not block LASO progress
LASO in this release is a defined mode, not a self-imposed honor challenge. It is Legendary difficulty with 17 specific skulls forced on, and it only appears in the campaign menus after you collect all 17. Finishing it grants MYTHIC, worth 50 Gamerscore on Xbox, a Steam achievement, or a Gold trophy on PlayStation. Halo Studios states that turning on any of the four difficulty modifiers stops those rewards from unlocking, and in co-op every Fireteam member must keep their preset set to None.
The gap the glitch relies on is that mission completion still gets written to your LASO progress while a preset is running. The achievement check and the progress counter are not reading the same state, so clearing a mission with maxed modifiers registers as a completed LASO mission once you refresh it through a clean checkpoint.
What you need before starting
Play LASO does not show up until you have every required skull, so there is no shortcut around the collection step. You need all 17 LASO skulls, which are 17 of the 39 hidden across the game, three per mission over 13 missions. The simplest route is to gather them on Easy during a normal story run, since collectibles appear regardless of difficulty.
Note: You are only unlocking the mode with these skulls. Once Play LASO is selectable in the Campaign and Campaign Remix menus, the glitch loop begins from inside that mode.
Modifier preset values
These settings keep you close to unkillable and remove ammo pressure, which is what makes each LASO mission trivial to clear. Enter them into one preset slot and leave the slot untouched between runs.
| Setting | Value |
|---|---|
| Damage Resistance | 2000% |
| Shield Recharge Rate | 200% |
| Damage Modifier | 300% |
| Melee Damage Modifier | 300% |
| Ammo | Bottomless Clip |
How to trigger MYTHIC progress
Tip: Always switch the preset to None before loading The Pillar of Autumn. The checkpoint only refreshes progress when no modifier is active during that step.
How to confirm it worked
Watch the MYTHIC achievement progress in the Xbox guide or the Steam overlay. Each completed mission moves it by roughly 7.7%, since the campaign runs 13 missions, so a single clear takes MYTHIC from 0/100 to about 7.7/100. Treat the checkpoint refresh, not the exact number on screen, as the part that matters after each run.
The ten main missions carry you to about 76% completion. The three bonus missions live in a separate LASO menu and take the last stretch up to 100%, at which point MYTHIC pops. Progress that fails to update usually means the preset was left on during the Pillar of Autumn skull step, or that mission’s clear did not register, both of which the skull refresh fixes.
Other achievements the loop moves
The same checkpoint behavior nudges several related campaign trackers, so the loop doubles as cleanup for other hard unlocks while it works.
| Achievement | How the loop helps |
|---|---|
| MYTHIC | Primary LASO campaign completion target. |
| Living Legend | Legendary campaign progress ticks up through the same runs. |
| Heroes Never Die | Heroic campaign progress ticks up through the same runs. |
| Mix Master | Campaign Remix no-death completion works with the same method. |
For Remix, the setup is identical except you only need any three skulls to unlock the mode instead of all 17. The Pillar of Autumn skull refresh registers Remix and Remix no-death progress the same way.
When this could stop working
This is an exploit against a rule the studio wrote a support article about, which makes it a clear candidate for a fix. The game reaches full release on 28 July, the same window a day-one patch would arrive, so there is a real chance it closes quickly. No patch date has been confirmed, so if you plan to use it, do it now rather than building a long-term plan around it.
Worth keeping in perspective: MYTHIC earned legitimately is one of the toughest things in modern Halo. Iron restarts the whole level on a solo death, Black Eye only recharges shields when you melee, Eye Patch removes auto-aim, Famine halves dropped ammo, and Fog kills your motion tracker, all stacked on Legendary. Clearing that for real and clearing it with 2000% damage resistance both put the same trophy on your profile, but they are not the same accomplishment.
