Aura (Japanese: 波導 wave-guiding) is Lucario’s fighter ability that modifies the damage and knockback of Lucario's moves based on its current damage, being weakened when Lucario is at low damage and strengthened when Lucario is at high damage. The aura mechanic only applies to Lucario (even if another character uses an aura attack), and starting in Smash 4, applies to all of Lucario's attacks regardless of whether they have the aura effect. When Kirby copies Lucario's Aura Sphere, he does not copy the aura mechanic; his Aura Sphere remains fixed at the power it would have if Lucario were at base aura strength (75% damage in Brawl, 70% damage in Smash 4, and 65% in Ultimate).
Lucario's aura is a special ability possessed by Lucario and there are various factors which determine how it works. Aura has three main stages; a floor percentage, a baseline percentage and a ceiling percentage. Each stage also has a damage multiplier, which determines how much damage an attack will deal compared to how much damage the attack is programmed to deal. The damage is calculated into the knockback formula, so aura can also have a rather drastic effect on knockback as well as damage. These stage percentages and multipliers vary from game to game, and the amount of damage Lucario's attacks deal is calculated by a mathematical equation, based on these percentages/multipliers.
Aura starts off at the floor percentage, where Lucario's attacks are much weaker than they are designed to deal. If Lucario is either at or below the floor percentage, the power of its attacks will match the floor multiplier. Once Lucario exceeds the floor percentage, its attacks will gradually become stronger as Lucario takes more damage.
When Lucario reaches the baseline percentage, all of its attacks will be at 1x power, matching the damage they were programmed to deal. Once Lucario exceeds the baseline percentage, the power of its attacks will continue to increase until it reaches the ceiling percentage, where its attacks will be much stronger than they normally would be. Once Lucario reaches the ceiling percentage, its aura cannot increase any further, regardless of how much more damage Lucario takes.
There is also an additional factor that affects how much aura Lucario has; the amount of stocks Lucario has in comparison to its opponents. If Lucario does not have the same amount of stocks as its opponents, it will have an additional aura damage multiplier. If Lucario has more stocks than its opponent, this multiplier will be below 1, making its attacks weaker. If Lucario has less stocks than its opponents however, this multiplier will be above 1, making Lucario's attacks stronger. This allows Lucario to have an even larger or lower aura multiplier, although Lucario also has a minimum and maximum aura multiplier, to prevent Lucario from building up incredibly high amounts of aura. These multipliers are 0.6x and 1.8x respectively (in every game as of Ultimate).
In Brawl, all of Lucario's aura-effect attacks are affected by the aura mechanic, which are most of its attacks. Lucario's attacks without an aura effect (including Extreme Speed, dash attack, back throw, down throw, and floor attacks) are not affected by aura, so they will always deal a set amount of damage. The strength formula is as follows:
where r is the percentage of the damage dealt (for example, if r is 80, the attack is at 0.8× strength) and d is Lucario's current damage.
Lucario's floor percentage is at 20% and its floor multiplier is 0.7x, so all of Lucario's aura attacks deal 0.7x their normal damage if Lucario is at 20% or lower.
Lucario's baseline percentage is at 75%, so all of Lucario's aura attacks will deal their normal amount of damage if Lucario is at 75%.
Lucario's ceiling percentage is at 170% and its floor multiplier is 1.4x, so all of Lucario's aura attacks deal 1.4x their normal damage if Lucario is at 170% or higher.
In addition to the above, the multiplier is multiplied again with a complicated factor based on Lucario's placing in the match and how many players there are (excluding CPUs). When Lucario's position changes, it takes 6.25 seconds for the new value to scale into full effect; if Lucario's position changes again during this time, the multiplier immediately skips to its new value. The mechanic is named Stock aura by players. The extra multiplier that Lucario receives from Stock aura is determined by the following formula.
In this formula:
This formula has an additional wrinkle in modes other than stock. In time mode, Lucario's lead/trail is equal to 1 until the difference between it and the leader/trailer is 5, at which point the lead/trail is 2. In coin mode, the value is 0 when Lucario is even and 2 otherwise.
For practical purposes, the most common multipliers in serious play are thus:
Despite these multipliers, the minimum amount of aura Lucario can have is at 0.6x power, while the maximum is at 1.8x power.
In Smash 4, the effect of aura has been increased overall. All of Lucario's attacks are now affected by aura, regardless of whether they have an aura hit effect or not. The stage percentages have been changed, in addition to the floor/ceiling multipliers also being changed. As a result, the aura formula has been changed, which can be seen below:
Lucario's floor percentage is now at 0%, although its floor multiplier is now only at 0.66x, so all of Lucario's attacks deal 0.66x their normal damage if Lucario is at 0%.
Lucario's baseline percentage is now at 70%, so all of Lucario's attacks will deal their normal amount of damage if Lucario is at 70%.
Lucario's ceiling percentage is now at a higher 190% however, its floor multiplier is now at a much higher 1.7x, so all of Lucario's attacks deal 1.7x their normal damage if Lucario is at 170% or higher.
Overall, this amounts to a buff compared to Brawl, except when Lucario is at a minuscule 8% damage or lower. This is because Lucario's Aura builds up faster and a maxes out at a much higher number without a stock deficit.
The aura stock formula remains unchanged, along with the minimum and maximum aura multipliers, although Lucario's Aura still scales differently due to the different formula.
Mega Lucario's aura attacks always deal 1.8× damage regardless of its current damage percentage. This is because Mega Lucario's minimum damage multiplier is at 1.8x rather than 0.6x, causing Mega Lucario to always be at 1.8x power, despite all other factors of its Aura being the same as regular Lucario.
In Ultimate, Aura has been slightly changed from how it worked in Smash 4:
As a result, the new formulae are r = 66 + (34/65)d for d ≤ 65 and r = 100 + 0.536(d - 65) for 65 ≤ d ≤ 190 (r = 100 + 0.48(d - 65) for 65 ≤ d ≤ 190 before patch 9.0).
Aura is a concept in the Pokémon franchise associated with Lucario, in particular in the movie Lucario and the Mystery of Mew. It functions as a supernatural sense, and can be channeled into the attack Aura Sphere.
Unlike in Super Smash Bros., aura in the Pokémon franchise has no relationship to becoming more powerful when damaged.