Modifiers

Check Out Modifiers on Destiny 2 Wiki

Modifiers change the difficulty of a Story Mission, Strike or Arena.

Modifier	Effect	Introduced
Airborne	Players deal more damage while in the air.	HoW
Arc Burn	Arc damage from any source is increased by 300%.	Original
Berserk	Minions of the Darkness won’t flinch, even after massive damage.	Original
Brawler	Guardian's melee damage is increased by 300%.	HoW
Catapult	Cooldown of Grenade abilities are greatly decreased.	HoW
Chaff	Player radar is disabled.	TTK
Daybreak	Reduces cooldown of all abilities. Epic is inherent.	AoT
Epic	Heavily shielded and highly aggressive enemies appear in great numbers.	Original
Exposure	Guardians' shields are increased but they do not regenerate.	HoW
Fresh Troops	Some enemy squads have been fortified with additional reinforcements.	HoW
Grounded	Players take more damage while airborne.	TTK
Heroic	Enemies appear in greater numbers and are more aggressive.	Original
Ironclad	More enemies have shields.	TTK
Juggler	No ammo drops for your equipped weapon.	Original
Lightswitch	Minions of the Darkness deal much more melee damage.	Original
Match Game	Enemy shields are resistant to all unmatched elemental damage.	TTK
Nightfall	If all players in your fireteam die, you will be returned to orbit.	Original
Small Arms	Damage of Primary Weapons is doubled.	HoW
Solar Burn	Solar damage from any source is increased by 300%.	Original
Specialist	Damage of Special Weapons is doubled.	HoW
Trickle	Cooldown of all of your abilities (grenades, melee and super) are increased.	HoW
Void Burn	Void damage from any source is increased by 300%.	Original

Please note that in Heroic and Epic Modifiers, the entire encounters are changed. More and more powerful enemies become available. They even have smarter A.I. Nightfall is similar to hardcore mode in other games. As soon as your fireteam wipes, you are kicked out of the mission or strike.