Mass Effect 3
68 Achievements
Combined Arms
Perform any combination of 50 biotic combos or tech bursts.
How to unlock the Combined Arms achievement in Mass Effect 3 - Definitive Guide
For this you need to use a combo of any of your special powers. You Do Not have to register a kill for this achievement. Just a combo to cause a Biotic Explosion or Tech Explosion.
You can even have your teammates use Stasis or Singularity and then use one of your own abilities. This will stack across Multiplayer and Single Player and should be easily picked up no matter what class you used. Just make sure when using your teammates you have them activate there powers first, then hit them with your own. Any power ability you use while another is active will register.
I found these to be easiest to attain with Tech Armor. You can have Liara shoot a Singularity bomb that will catch a few enemies, then run up and detonate the Tech Armor. It will hit all enemies and register each enemy as a combo.
For Soldiers I would recommend using Cryo or Incendiary Rounds. Once the target is on frozen/ on fire, then use Concussion shot. This will register for you.
EDIT: According to Hasharin, the Normandy will show up anyways even if you don't fire a shot. Maybe there's also a kill counter involved? I don't know, but he was able to get 30 combos out of it, so it's a good start.
A combo indicates you have used 2 powers on the same enemy, one after another. These should come naturally. There are many combos and you'll probably use them without thinking. An example is Singularity which raises an opponent up, then using Throw to knock the enemy flying. A tech burst is basically a weapon power. Both powers have to be of the same type to raise the counter (using a biotic Singularity and then a tech Incendiary won't count, for instance) and at least one needs to be done personally by you.
Note: Even after dying, the ones you have obtained count. They count across all playthroughs as well as multiplayer (which you can play by yourself).
Like Mass Effect 2, there are certain powers that when combined with another can have a devastating effect. For some, the enemy that you target must be killed by the combination. Unlike ME2, there are also combinations with tech powers. Below is a list of biotic and tech combinations. The list comes from Relix on the Bioware forums.
BIOTIC COMBOS
We all know the drill, cast a biotic power on an enemy, and once an enemy is affected by it, finish it off with another biotic power for a damaging AoE explosion.
Notes:
-Not all biotic powers are compatible with each other (E.G. Singularity --> Pull will not cause a biotic combo).
-Stasis is unique, because it can bypass defenses (such as shields and barriers), and enemies can be detonated while their defenses are still present. It is, however, completely ineffective vs. armored targets such as Atlas mechs and Turrets.
-Warp & Reave are unique because they can either set up or set off biotic combos. They can also set up combos on enemies with defenses (shields/barriers), so they functions similar to Stasis in this regard. And they are the only two biotic powers in the game, able to set up combos on armored targets, such as Turrets and Atlas mechs.
List of biotic combos below.
-Sigularity --> Warp/Throw/Shockwave/Charge/Nova/Cluster Grenade/Reave
-Stasis --> Warp/Throw/Shockwave/Charge/Nova/Cluster Grenade/Reave
-Pull --> Warp/Throw/Shockwave/Charge/Nova/Cluster Grenade/Reave
-Warp --> Throw/Shockwave/Charge/Nova/Cluster Grenade/Reave
-Lift Grenade --> Warp/Throw/Shockwave/Charge/Nova/Cluster Grenade/Reave
-Shockwave (only with Rank 6 Lifting Shockwave evolution) --> Warp/Throw//Charge/Nova/Cluster Grenade/Reave
-Reave - Warp/Throw/Shockwave/Charge/Nova/Cluster Grenade
ELEMENTAL (aka tech) COMBOS
There are also some new combos in ME3, that involve Tech or Combat elemental based powers. It's the same principal as with biotic combos, but they function in a slightly different manner.
FIRE EXPLOSION
-Can be set up by: Incinerate, Carnage, Inferno Grenade, Incendiary Ammo
-Can be detonated with any Biotic/Tech/Combat powers that can deal direct damage (except for the powers that are used to set up the combo).
-Effect: Enemies effected by any of the fire based powers, cause an AoE fire explosion, once they are killed by a direct damage power. The effect is similar to blowing up Pyros with Overload in ME2.
-Note: Enemy MUST be killed by the second power, in order to cause a Fire Explosion. E.G. it will not work, if an enemy is hit by Incinerate --> Overload, and still has HP left after that. So, in this case, Overload would have to do sufficient damage to outright kill a burning enemy, in order to cause a Fire Explosion.
CRYO EXPLOSION
-Can be set up by: Cryo Blast, Cryo Ammo
-Can be detonated with any Biotic/Tech/Combat powers that can deal direct damage.
-Effect: Frozen enemies killed by damage based powers, cause an AoE cryo explosion, freezing any enemy that is nearby.
-Note: Same as Fire Explosion, frozen enemies MUST be killed by the second power in order to trigger Cryo Explosion.
TECH BURST
-Can be set up by: Overload, Energy Drain, Disruptor Ammo, Sabotage
-Can be detonated by any Biotic/Tech/Combat powers that can deal direct damage (except for the powers that are used to set up the combo).
-Effect: Enemies effected by electricity based powers, discharge multiple electricity bolts to nearby enemies, when hit with direct damage powers. Effect is similar to Overload's Chain Overload upgrade.
-Note: Unlike Fire & Cryo Explosion combos, this one doesn't require an enemy to be killed by the second power. E.G. enemy hit by Overload --> Incinerate will produce Tech Burst, whether he is killed by Incinerate or not.
Source: Choose Language | BioWare Social Network
BIOTIC COMBOS
We all know the drill, cast a biotic power on an enemy, and once an enemy is affected by it, finish it off with another biotic power for a damaging AoE explosion.
Notes:
-Not all biotic powers are compatible with each other (E.G. Singularity --> Pull will not cause a biotic combo).
-Stasis is unique, because it can bypass defenses (such as shields and barriers), and enemies can be detonated while their defenses are still present. It is, however, completely ineffective vs. armored targets such as Atlas mechs and Turrets.
-Warp & Reave are unique because they can either set up or set off biotic combos. They can also set up combos on enemies with defenses (shields/barriers), so they functions similar to Stasis in this regard. And they are the only two biotic powers in the game, able to set up combos on armored targets, such as Turrets and Atlas mechs.
List of biotic combos below.
-Sigularity --> Warp/Throw/Shockwave/Charge/Nova/Cluster Grenade/Reave
-Stasis --> Warp/Throw/Shockwave/Charge/Nova/Cluster Grenade/Reave
-Pull --> Warp/Throw/Shockwave/Charge/Nova/Cluster Grenade/Reave
-Warp --> Throw/Shockwave/Charge/Nova/Cluster Grenade/Reave
-Lift Grenade --> Warp/Throw/Shockwave/Charge/Nova/Cluster Grenade/Reave
-Shockwave (only with Rank 6 Lifting Shockwave evolution) --> Warp/Throw//Charge/Nova/Cluster Grenade/Reave
-Reave - Warp/Throw/Shockwave/Charge/Nova/Cluster Grenade
ELEMENTAL (aka tech) COMBOS
There are also some new combos in ME3, that involve Tech or Combat elemental based powers. It's the same principal as with biotic combos, but they function in a slightly different manner.
FIRE EXPLOSION
-Can be set up by: Incinerate, Carnage, Inferno Grenade, Incendiary Ammo
-Can be detonated with any Biotic/Tech/Combat powers that can deal direct damage (except for the powers that are used to set up the combo).
-Effect: Enemies effected by any of the fire based powers, cause an AoE fire explosion, once they are killed by a direct damage power. The effect is similar to blowing up Pyros with Overload in ME2.
-Note: Enemy MUST be killed by the second power, in order to cause a Fire Explosion. E.G. it will not work, if an enemy is hit by Incinerate --> Overload, and still has HP left after that. So, in this case, Overload would have to do sufficient damage to outright kill a burning enemy, in order to cause a Fire Explosion.
CRYO EXPLOSION
-Can be set up by: Cryo Blast, Cryo Ammo
-Can be detonated with any Biotic/Tech/Combat powers that can deal direct damage.
-Effect: Frozen enemies killed by damage based powers, cause an AoE cryo explosion, freezing any enemy that is nearby.
-Note: Same as Fire Explosion, frozen enemies MUST be killed by the second power in order to trigger Cryo Explosion.
TECH BURST
-Can be set up by: Overload, Energy Drain, Disruptor Ammo, Sabotage
-Can be detonated by any Biotic/Tech/Combat powers that can deal direct damage (except for the powers that are used to set up the combo).
-Effect: Enemies effected by electricity based powers, discharge multiple electricity bolts to nearby enemies, when hit with direct damage powers. Effect is similar to Overload's Chain Overload upgrade.
-Note: Unlike Fire & Cryo Explosion combos, this one doesn't require an enemy to be killed by the second power. E.G. enemy hit by Overload --> Incinerate will produce Tech Burst, whether he is killed by Incinerate or not.
Source: Choose Language | BioWare Social Network
We go through the omega dlc and after it we go to the med. sector and there we select a biotics skill called whip (allows you to knock the enemy down with a biotic whip, causing average damage) and in battle together with Liara or Javik we use biotic skills.
Class examples:
Soldier. Shoot at the enemy with freezing or incendiary cartridges. When the enemy freezes/burns, use the Stunning Shot skill - it will count.
Guardian Activate "Technical Armor", lift several enemies into the air with Liara's "Singularity" skill, run up to the hovering heroes and deactivate the armor, causing a blast wave. One will be counted for each person hit by the wave.
There are plenty of combinations for all classes. Find one more convenient for you, repeat 50 times and the achievement is yours.