A modifier (also known as a buff) is a statistic that adds a bonus to an attribute of a character in combat zones. There are standard and elite modifiers, with the latter granting a greater bonus. They are awarded by companions.
The Elite versions below are denoted by an asterisk (*).
Critical Damage Up[]

Increases the damage incurred on a Critical Hit.
Critical Hit Up[]

Increases the chance of achieving a Critical Hit against an enemy.
Defense Up[]

Decreases the amount of damage a player takes from enemy attacks.
Force Regen Up[]

Increases the speed of Force regeneration.
Force Up[]

Increases the maximum amount of Force from 250 to 300. The elite increases the maximum to 350.
Health Regen Up[]

Increases the speed of Health regeneration.
Health Up[]

Increases the maximum amount of Health from 10,000 to 10,500. Elite Health Up companions increase maximum Health to 10,700.
Speed Up[]

Increases the player character's running speed.
Post-Revival Invulnerability[]

Temporarily makes players invincible to all enemy attacks.
This Modifier is only available for a few moments after a player revives either for free at the Republic outpost or where they are after being knocked out.
Enemy Credit Rewards x2[]

ncreases the amount of Republic Credits received from defeating enemies, completing Collections, and Republic Credit orbs.
This Modifier can only be earned by defeating the CIS dropship on Umbara. After it is defeated, all players in the area will receive it, even if only one shot is fired and the player leaves the area.