Synth up: no ammo drops at all

Iron. If any player dies entire team is sent to orbit. [spoiler]ah ye old Halo days[/spoiler]

[u][b]The Legend[/b][/u] [i]The Last Guardian Standing deals extra damage.[/i] [u][b]Danger Close[/b][/u] [i]Friendly Fire is enabled.[/i] [u][b]Malfunction[/b][/u] [i]Radar is disabled in Restricted Respawn Zones.[/i] [u][b]Energy Focus[/b][/u] [i]Super does not charge, but all other abilities recharge significantly faster.[/i] [u][b]Steady Hand[/b][/u] [i]Increased Precision Damage. Decreased Non-Precision Damage.[/i] [b][u]The Endless Night[/u][/b] [i]Fallen Fireteam members will be sent back to Orbit individually if not revived within 15 seconds. Fireteam joining is disabled at the start of the game.[/i] [u][b]Steel Rain[/b][/u] [i]Hip shooting grants extra damage to Primary Weapons.[/i]

All of the modifiers you listed above are terrible. Sorry but most of them are game breaking bad the others would just be tedious.

Leech : [spoiler]your health doesn't regenerate, but grenade hits replenish a bit of your health. ( negates the use of Red Death, Suros Regime, Titan Storm Fist Transfusion, Blink Strike from Bladedancer, Apotheosis Veil for Warlocks, and Life Steal from Voidwalker )[/spoiler] Light's Reign : [spoiler]Supers, Grenades, and Melee abilities have increased damage/duration ( 100% damage for supers, 25% increased duration for supers/grenades, 75% damage for melee abilities, and 30% damage for Grenades ) but use of these abilities leave a debuff that reduces the charge rate of your abilities for a short time ( maybe called "Light's Retreat"? )[/spoiler] Dark Atmosphere : [spoiler]All guardian movement speed is reduced by 33%, jump height also reduced by 33%[/spoiler] Scorched Earth : [spoiler]Enemies will not drop ammo. Grenade hits and supers replenish a small portion of ammo on equipped gun. Grenade recharge rate increased by 25% ( Icebreaker and Bad Juju are good options to use under this modifier )[/spoiler] Stealth Shot : [spoiler]While crouched, Guardian Accuracy is increased by 100% and Guardian Stability is increased by 50%. Guardian also deals 33% increased damage.[/spoiler] Last Stand : [spoiler]Guardian Abilities recharge 100% faster while shield is down. However, abilities deal 25% less damage while shield is down/ duration reduced by 25%[/spoiler] Juggernaut : [spoiler]Fewer enemies face you, but are much stronger and more aggressive. ( all majors, 33% less enemies than normal, much more likely to pursue you in cover or while attacking from a point. )[/spoiler] Light Amplifier : [spoiler]Orbs of Light replenish your super by twice the normal amount. Super recharge rate reduced by 33%[/spoiler] All I got for now, maybe I'll put some more when I think of some.

Stone age: All of your weapons are now temporarily replaced with Uncommon (Green) weapons! But all enemy damage is reduced to what a lvl 20 enemy would do. Melee and Projectiles

Story Mode: When you kill an enemy your ghost tells you the origins of that enemy [spoiler]yeah I went there[/spoiler]

Gjallar-muned: all enemies are immuned to gjallarhorn. "Best" modifier on crota :)

legendary burn legendary weapons do more damage

Shia surprise: After you think the boss is dead, the boss will spawn next to you with its gun to your head when you don't expect it

Can't think of names for them. 1:Supers do not charge. 2: Heavy weapons do 2x less damage. 3: Exotic use is restricted. [spoiler]Imagine having all 3 at once.[/spoiler]

"Fight me" no ammo and melee only with 2x damage

Mortal: no revives, no abilities.