Back, Aerial, Chase, and Down are Attack Judgments. When the player triggers an Attack Judgment, stats related to the respective judgment will be applied to the attack that triggered the judgement.
To trigger, attack the foe when your character is positioned on the side opposite of which the foe is facing. The actual attack does not need to hit the foe's back side. Attacks will count as back attack as long as your character is on the side that is the opposite of which the foe is facing.
For example, even if you fire off Levia's Finishing Move Walpurgis and the attack is striking the foe's front side, as long as you move Levia to the opposite side of which the foe is facing, hits from Walpurgis will begin to count as Back Attacks.
Even when flinching to attacks, enemies tend to turn around to defend themselves against back attacks very often. To alleviate this issue, strike the enemy when they use a move that takes a while to cast and has high Super Armor Crash level, or Chase the foe; foes cannot change direction when mid-air.
To trigger, attack while your character is mid-air.
Your character must have been mid-air at the time of cast.
If your character was on the ground, but the skill sends you to the air (such as using Rolling Vulcan! or Advanced Reversal on the ground), the hits where you are in the air will NOT count as Aerial.
The opposite is also true: If you used a skill in the air, but the skill sends you to the ground (e.g. Zone Control or Calcium Charging), the ground hits WILL count as Aerial.
Unlike other situations, Aerial is binded with the action you preform.
For example, if Finishing Move Walpurgis were to be used on ground, even if you jump up, the skill's hits will not count as aerial because the skill was casted on the ground.
To trigger, you must hit the foe while they are mid-air. Tina's attacks will trigger Chase so long as Tina is on the ground.
Be advised that there are many foes (mostly bosses) that cannot be launched or lifted, and as such, getting Chase bonuses on them is impossible (except for Tina).
To trigger, you must hit the foe when they are in Knocked-Down State.
Some skills are able to immediately make the foe stand up again from Down state, however, such as the following:
- Skills that crash Super Armor
- Grabs, if the foe is grabbable
- Various skills with re-standing effect, such as Electronic Storm, Anion Punch, Follow Me!, Pulverizing Blade, Serpent's Waltz, etc. Note, however, that some skills capable of re-standing in PvE don't have that effect in PvP. 
|Gameplay||Modes||Union Arena (PvP) ▪ New Seoul (PvE)|
|Mechanics||Super Armor ▪ Status Effects ▪ Skill Cube ▪ Skill Chain ▪ Experience Table ▪ Attack Judgement ▪ Monster Types|
|System||PNA ▪ Teamwork Skills ▪ Union Watch ▪ Black Market ▪ Storage ▪ Stats ▪ Circle ▪ Pets ▪ Stamina ▪ Achievements|
|Raids||Tiamat Raid ▪ Irina Raid ▪ David Raid ▪ Purification Ops ▪ Wolfgang Raid|
|Items||Equipment||Equipment Slots ▪ Grades ▪ Enhancing ▪ Tuning ▪ Dismantling ▪ Chips|
|Costume||Costumes ▪ Signature/Rare Costumes ▪ Accessories ▪ Fibers, Upgrading, & Tuning|
|General||Potions ▪ Sealing ▪ Union Store ▪ Material Conversion|
|Other||Teams||Black Lambs ▪ Wolf Dogs ▪ Wildhüter|
|Story||Story ▪ NPC|
|Etc.||Server Differences ▪ Emotes and Poses ▪ Animation ▪ Fan Terms ▪ Union Medal|