Alright say a skull that has aready been made and which game its from you want tobe in halo 4 then make one that you would want.
say the name then the skulls effect. If it would be primary or secondary, and how the player would obtain it.
Alright here is mine:
Skull: Curveball(Secondary)
Effect: grenades always curve
How to obtain: Finish level on heroic with no grenadesthrown and pick it up on a ledge u have to jump to.
Clusterskull
Allows gernades to explode into a cluster of like 12 of them. XD
Yeah that would be awesome. good idea.
i would have been your mommy
same effect as iwhbyd but everyone has a high pitched voice
betrayskull turns a random type of enemy such as grunts in halo reach on your side.
Crack head (secondary [the skull would have a crack on an eye hole, like how black eye has a dark eye hole])
When you take damage your visor will gain a crack, makeing it harder to see, but the cracks disapear when healing.
Optain: on hard difficulty don’t deliver shoot to the head or receive, even if they arn’t going to kill you.
or when a team member betrays you on death they spawn as a grunt with no guns
SugarHigh:
Effect: Headshoted grunts -Yoink!- out
Found: 343 reward
My homeworld Needs me:
Effect: Killed Jet-pack enimies fly directly up when you kill them…and don’t come down
Found: near a pre-placed Dead Elite
Cannon Fodder army:
Effect: Only grunts…Just grunts
Found: in a random sentinel
random ideas, i don’t expect them to be popular
I Didn’t Start the Fire
All projectiles, explosives, and melee attacks ignite all enemies and vehicles in flames. Watch where you throw those grenades, though–you don’t want to catch yourself on fire.
Location: completely random throughout the campaign.
I said this back in one of the threads wanting Johnson to come back.
The Johnson skull:
Effect: All allies are replaced by Sgt. Johnson, dialog and all.
Bubble skull: When a plasma grenade o frag grenade explodes, it becames 12 grenades (the explosion throw them in different directions) of each type, and then they explode normally
Switcheroo
-all unsc turn into covenant
-all covenant turn into unsc
-and all other factions switch
Hola
-has the same effect as IWHBYD except all voices now have a mexican accent and A.I.s will say mexican things like “I wanna taco” or “toro toro” (not raciast just love the accent)
-Crack
Effect: Your Helmet cracks by being hit (like in Lone Wolf) and your HUD starts flickering. The Damage won’t disappear till you die.
Almost the same Idea like PhoneixFire57 had.
i got one its called
Administration and when its activated you recieve no in game guidence, like cortana or kat telling you where you need to go, you just have to figure it out and you beat all 3 missions on ledgendary.
-Thunderstorm
Effect: Drains your shields randomly every couple minutes.
-Fleet feet
Effect: Enemy movement speed is increased by 25%.
Big Things, Small Packages.
Effect: Magnums shoot Sniper rounds and Charged Plsma Pistol shoots a Spartan laser shot.
How to get: Complete a level of the campgain on legendary useing only small arms.
> Big Things, Small Packages.
>
> Effect: Magnums shoot Sniper rounds and Charged Plsma Pistol shoots a Spartan laser shot.
> How to get: Complete a level of the campgain on legendary useing only small arms.
Wow that’s crazy… and awesome dude! 
-Commando
Effect: Other skulls are active for your allies as well as the enemy. For example, if you turn Catch and Thunderstorm on along with Commando, all your allies will be ODSTs and throw grenades 2x as often.
HurrySkull:
There is a set time limit that the level must be finished in, the higher the difficulty the less time that is available.
Ashes (secondary)
Killing any enemy with plasma/energy based weapons causes them to disintegrate.