Skulls in Halo: CE act like modifiers that impact your game. You can choose to turn them on for a greater challenge or to make things a little easier. They can impact the game in various ways to make it more fun to play. Previously, skulls needed to be collected from specific locations in the game, but now you can activate them all from the main menu in the Master Chief Collection.
To activate skulls in Halo: CE, click on the mission you want to play in the missions menu, then click on the skulls tab. From there, you can click on each skull to activate it and then click on Accept Skulls to confirm your choices. All the skulls will have various modifiers, and score multipliers, attached to them.
All Skulls and their modifiers
Skulls are broken into two groups, Scoring and Non-Scoring.
Scoring
| Skull | Modifier | Multiplier |
| Anger | Enemies fire their weapons faster and more frequently. | 1.10x |
| Black Eye | Your shields only recharge when you melee enemies. | 1.10x |
| Blind | HUD and weapon do not display on screen. | 1.10x |
| Catch | Enemies throw and drop more grenades. | 1.10x |
| Eye Patch | Auto-aim features disabled for all weapons. | 1.10x |
| Famine | Weapons dropped by AI have half ammo. | 1.20x |
| Fog | The motion tracker is disabled. | 1.10x |
| Foreign | You cannot use or pick up Covenant weapons. | 1.10x |
| Iron | Dying in coop resets you to the last checkpoint. Dying in solo resets the mission. | 1.30x |
| Mythic | Enemies have increased health. | 1.20x |
| Recession | Every shot takes twice as much ammo. | 1.20x |
| That’s just wrong | Increases enemy awareness of the player. | 1.10x |
| Thunderstorm | Upgrades the rank of most enemies. | 1.20x |
| Tough Luck | Enemies always go berzerk, dive out of the way, and never flee. | 1.10x |
Non-Scoring
| Skull | Modifier | Multiplier |
| Bandana | Infinite ammo. | 0.00x |
| Boom | Explosion radius increased x2. | 1.00x |
| Ghost | AI no longer flinch from attacks. | 1.00x |
| Malfunction | Everytime you respawn, a random HUD element is disabled. | 1.00x |
| Grunt Funeral | Grunts die in a blaze of glory. | 1.00x |
| Grunt Birthday Party | Grunt headshots lead to glorious celebrations. | 1.00x |
| Pinata | Punching enemies makes them drop grenades. | 1.00x |
| Sputnik | Mass of objects is decreased. | 1.00x |
