CO Power

CO Powers are a gameplay element from the Advance Wars series. They are individual abilities that Commanding Officers can activate occasionally in a battle in order to get an advantage.

In Advance Wars

CO Powers debuted in Advance Wars. Each CO had one power each. Powers built up as units took and inflicted damage. Each CO Power meter was worth a certain amount of damage, with damage inflicted being worth 1/4th as much as damage received.

As well as a set of unique effects per CO, activating a CO Power also gave every one of that CO's units a 10% boost in firepower and defence. This boost is known as the "standard boost".

Note that in Advance Wars 1, boosts or reductions in power are multiplicative, so if you have a 10% boost on top of a 120% attack, it becomes 1.2 x 1.1 = 1.32 for a new 132% damage attack. Similarly, for defence, it multiplies by less than 1, such as x0.9.

In Advance Wars 2: Black Hole Rising

CO Powers returned in Advance Wars 2: Black Hole Rising, which are used mostly in the same way as before, but with a second level of CO Power and some slight tweaks. The gauge's display is now a set of small and large stars lined up horizontally instead of a single continuous gauge that wrapped around the funds and portrait. Only once the first large star is filled can a CO Power be used. Each star represents 9,000G's worth of funds, and the minimum amount of gauge required to use a CO Power changed accordingly per CO (for example, Max now requires 27,000G (3 stars) to use his CO Power instead of 30,000 from AW1). Meter gain was also updated to give the attacker 1/2 the cost of the unit, up from 1/4 from AW1. Additionally, a new second level of CO Power was introduced as the Super CO Power, which requires the entire bar of stars to be filled, instead of just the first large star. Super CO Powers are typically stronger versions of the CO Power, but there are some exceptions where the two powers can have different effects.

The standard boost was changed to increase only defence by 10% without increasing attack power.

Note that starting from Advance Wars 2, boosts and reductions in damage changed from multiplicative to additive. So, a 20% boost on top of a 110% damage attack makes it 130%.

In Advance Wars: Dual Strike

Advance Wars: Dual Strike changed the formula slightly again. Rather than making stars represent a monetary value, each unit was given a rating of how many stars it was worth. A third psuedo-tier of powers was also introduced: the Tag Power. A Black Hole idea, Tag Powers allowed two Super CO Powers to be used back-to-back in a single turn. The first CO would initiate the Tag Power and use their Super Power, then play their turn as usual. After they had finished, they would select CO Swap from the menu and each unit would get a second turn, under the effects of the second CO. On top of that, an attack modifier was applied depending on how well the two COs got on in the story.

The standard boost once again improves both attack and defence by 10%..

Note that Dual Strike keeps the additive boost application introduced Advance Wars 2.

In Advance Wars: Days of Ruin

The entire way COs worked in general was changed for Advance Wars: Days of Ruin. COs can board a unit from the HQ or production property for half of the unit's build cost. Once boarded, the CO Zone will appear around the unit, applying the CO's personal effect as well as a 10% firepower and defense boost to their units within it. The power meter charges based on damage in HP dealt to the enemy when any unit within the zone initiates combat. Each tick represents 6HP and after 30HP, the first bar is filled, expanding the zone by one space. Dealing another 30HP extends the size of the zone by one space again and allows the CO Unit to end its turn to activate the CO Power. In addition to the CO Power effect, Powers also extend the CO Zone to the whole map. Using a CO Power will completely drain the meter and reset the Zone size. The destruction of the CO Unit will also reset the power meter. COs Forsythe and Caulder do not have powers and cannot expand the size of their CO Zones.