These are powerful finishing attacks that only require two types of attacks: Primers (attacks that prepare the target for a combo) and Detonators (attacks that trigger/ activates the combo). Powers and power upgrade will have icons that will identify if they are primers or detonators.
To perform a Power Combo, shoot the target with a primer move then follow up immediately with a detonator move.
There are four types of power combos: heat, cold, tech, and biotic which is determined by the primer. For example, an enemy set by a heat/fire primer will always result to a heat combo no matter what detonator you use. This easy set up makes it easy to pull off power combos right off the bat. Power combos are also considered as an “extra” attack that deals additional damage on top of the damage dealt by the primer and detonator attacks. Also, power combos are identified as AoE (area of effect) explosions.
Heat combos are treated as incendiary damage from the ignition up to the succeeding DoT (damage-over-time) burn effect that continuously damages the target for a few seconds after getting hit.
Primers:
Cold detonations will have an AoE effect, dealing moderate damage while also slowing down enemies within the blast area. Armored enemies also take bonus damage while affected by this debilitating effect.
Primers:
These are electric / shock attacks that can deal high damage to shields but not as much to health and armor. These combos also leave a lingering electrical discharge in its area where it was detonated dealing extra DoT and stunning enemies in the immediate area.
Primers
Unlike the elemental combos above, this is just a single burst of damage. However, R5 (rank 5) Containment, the biotic passive skill, can knock down unarmored, unshielded, and normal-sized targets upon detonating a biotic combo. Also, when the adept profile is active, biotic combos will have extra AoE explosions for each enemies hit by the initial combo detonation.
Primers
Source: Prima eGuide