The big yellow bar at the top of the HUD shows each character's health. There are two types of health in this game: Yellow Health (regular health), and Blue Health (recoverable health).
Once yellow health is reduced to 0, that player loses the round. If yellow health is reduced to approximately 35% the character enters Awakening.
Blue health is health that is temporarily lost and will regenerate over time. However if an opponent hits a character with blue health then the remaining Blue Health is lost. This is similar to damage absorbed by Focus Attacks in Street Fighter 4.
There are a variety of ways to transform regular health into blue health:
Super Cancels and Furious Actions are still usable at low life, essentially making them free since regardless you will likely lose the round if the opponent is able to hit you. Players should take note of this fact and prepare to see Furious Actions when the opponent is near death.
Note that a character can not die from having only blue health. This means that unlike most other games, a character can not die from blocking special and super attacks. Blue Health is not counted when determining winner by time out: only the yellow section counts.
There is approximately 5 second startup before Blue Health starts to recover. The startup is reset if you receive more blue damage, or if you block anything. However, this delay is not affected by jumping or any offensive actions.
Getting hit by attacks that do zero damage (such as Bursts, and throw breaks) will not remove your Blue Health.
Once Health is reduced to approximately 35% or lower and the character returns to a neutral or blocking state, then the character will enter Awakening. Awakening has a visual effect when it occurs: the character will flash orange, his/her portrait will appear briefly in the background, and the character's life bar will turn a darker shade of yellow.
While in Awakening, the character will receive the following bonuses:
- A defensive boost: all damage is reduced to 62.5%. Meaning hitting the opponent with a 1000 damage attack would only inflict 625 damage when the opponent is in Awakening.
- This even applies to minimum damage! An attack that does 1000 minimum damage would only do 625 minimum damage when in Awakening.
- SP gauge max becomes 150 instead of 100.
- Free 50 SP.
- Unlock new super attack(s), which varies from character to character.
Because a character will not go into Awakening until they are low on life AND return to neutral state, a common tactic is to do a high damage combo when the opponent is near Awakening so the opponent will have as little life as possible with Awakening's defense boost. You can even stop the opponent from going into Awakening by doing a combo that outright kills the opponent before the health condition is met!
You can also force yourself into Awakening by performing a Super Cancel or Furious Action if it puts your regular life below the Awakening threshold, then recover the Blue Life while receiving Awakening's defense boost! Elizabeth is a prime candidate to do this with Mind Charge and Diarahan.
As you combo an opponent you will notice that each attack's damage tends to go down over the course of a combo. This property is known as damage scaling and is used to make it so that combos are not too damaging, and to balance out certain attacks by reducing the amount of damage possible off said attack.
For every move in your combo after the first, a character-specific modifier is applied to scale down the damage more than it otherwise would be. Combo Rate varies between 0.5 (Shadow Labrys) and 0.75 (Akihiko). So, for Shadow Labrys, every move after the first does 0.5 times its normal damage, in addition to scaling from proration.
Each attack has three values, P1, P2, and SMP, meaning Proration 1, Proration 2, and Same Move Proration. These modify the damage of every move used after them in a combo. During a combo, a Proration Tally (PT) is kept. After a move hits, its proration is added PT as such:
- If it was the first move in the combo, add P1 and P2; otherwise, only add P2.
- Add SMP as well if the move had previously been used in the combo.
For every 100 PT, damage is reduced by 4%, up to 1200. Starting at 1300, damage is reduced by 2% per 100 PT. Intermediate numbers are not counted; there is no difference between 400 PT and 450 PT, for instance, but adding another 50 would make it 500, which would add to scaling.
- Example 1: Say you use a move with 200/100/50 as the starter and the second attack in a combo. So for the third attack, you have (200 + 100) + (100 + 50) = 450 PT. Counting only the hundreds, damage is reduced by 4 * 4% = 16%.
This value is subtracted from 100%, and the resulting number is multiplied by base damage and, for all moves beyond the first in a combo, Combo Rate.
100% - this value can also be called Effective Proration; EP for short. EP is bound by 0% and 100%, meaning you'll never do negative damage or do more damage than normal. Some attacks do have negative proration, for instance "One More Burst" for all characters has a P2 of -200, while Naoto's "Mudoon" has a P2 of -600 (but an SMP of 2500), but if your PT is below 0, your EP will still only be 100%.
The damage formula, in total: Base Damage * Combo Rate (or 1 for first move) * Effective Proration
- Example 2: You've done some combination of moves so that PT is 1550 and want to see how this affects the next move you do. Divided by 100 = 15. Multiply the first 12 by 4% = 48%, leaving 3; 3 * 2% = 6%. EP = 100% - 48% - 6% = 46%.
If the next move you want to do has 800 base damage and your character has a 60% combo rate, your attack will do 800 * 60% * 46% = 220 damage.
Same Move Proration Glitch
Also existing in BlazBlue CS Series, the SMP glitch is much easier to trigger in Persona 4 because here, EVERY move has SMP! It works like this: When a move with SMP is used for the first time, it is put in a list that holds at most 10 attacks. Any moves with SMP beyond the 10th are NOT STORED. So, after performing 10 different attacks, SMP is not applied for all subsequent attacks, since the game is unable to recognize that they've already been used in the combo. Many characters can make use of this in some way, but it's particularly useful for Naoto: 
Note also that some moves count multiple times for proration if they have multiple parts to them. For instance, All Out Attack to All Out Rush to All Out Finish counts as 3 separate attacks, while for Naoto's gunfire the first 4 bullets and the 5th bullet are counted separately. As well, the different versions of special moves are all considered separate attacks. This can make it much easier to trigger the SMP glitch for several characters.
Similar to BlazBlue, some attacks (and most supers) deal a minimum amount of damage in a combo. This means that past a certain point, some attacks attacks will ignore damage scaling and deal at least a certain percentage of their base damage.
For most supers this is 30% of their base damage, but there are exceptions. This means that super attacks are great as combo finishers since they will ignore some of the damage scaling and deal damage that otherwise would not be available.
Power up supers like Yosuke's Sukukaja, Chie's Power Charge do not get the benefits of Minimum Damage.
Minimum Damage is still affected by Awakening. Meaning if an attack would normally do 1000 minimum damage, it would only do 625 minimum damage when the opponent is in Awakening.
Additional Damage From Counter Hits
Getting a Counter Hit increases the base damage of normals and specials by 10%, and of supers by 20%! The rules are described in more details here.
Similar to damage scaling, the amount of hitstun and untechable time each attack deals will scale down with damage scaling. This is meant to act as a means to prevent infinite combos, but also requires that players understand a deeper level of their character's combo theory due to the fact that combos that worked earlier may not any longer due to hitstun decay.
Hitstun and untechable time scaling is based on damage proration. As proration passes certain thresholds, hitstun and untechable time go down by a specific amount of frames. For untechable time, it works like this:
Prior to 52% proration, untechable time is not reduced.
|Proration Tally||Effective Proration||Hitstun||Untechable Time|
Moves cannot have their untechable time reduced below 1F. At any point if a move should have 0F untechable time, it is untechable for 1 frame. Throws and some rare other moves also have fixed hitstun/untechable time, which isn't reduced in this way.
Hitstun is not reduced at the same rate as untechable time; it takes longer for a move to have its hitstun reduced than its untechable time. However, as of this writing the rate of hitstun reduction is not known.
Also note: Hitstop is not reduced by hitstun scaling, so there may be other ways to perform combos even after you reach the maximum reduction (i.e. using the hitstop from projectiles which only gets applied to the opponent and not the attacker, etc.).
- Crouching Opponent
- Hitting a crouching opponent give an additional 2 frames of hitstun. This means that there are combos that only work on crouching characters, for example, Narukami can combo 5C > 2C on crouching characters but not on standing characters.
- Fatal Counter
- Fatal Counters adds 5 frames of hitstun/untechable time to all subsequent attacks in that combo. This allows for combos that would otherwise not work. For example, Yosuke can not usually combo after Mirage Slash, but with a Fatal Counter beforehand, he can combo from Mirage Slash into a 2A!
- Fatal Counter does not stack, so doing two Fatals in one combo still only adds 5 frames instead of 10.
Valid vs. Invalid Combo
Because characters can choose to delay their ukemi, this leads to the possibility of combos that work only because the opponent decided not to ukemi. This means that some combos are not "true" combos; the game's HUD differentiates between the two classes of combos by showing the hit counter as red for a valid combo and yellow for an invalid combo. The invalid combo HUD also show which hit was invalid.
There are some situations on defense where you intentionally delay an ukemi to avoid a mixup. For example, some characters often create mixups assuming you will ukemi right away. Delaying your ukemi will mess up their timing and allow you the chance to escape.
A valid combo versus an invalid combo. The small yellow number at the bottom shows which hit was invalid.