Add-on Skills

Add-on Skills are a mechanic that serve as a way to make your characters stronger after you reach class level caps. Gaining enough EXP at max level will reward you with Class N-EX-Cubes, which can be spent at the Class Counter to get specialized bonuses themed after each class.

Each Add-on Skill you unlock is an immediate, permanent, account-wide bonus. Furthermore, every Add-on Skill set grants a 1% bonus to EXP earned, Meseta gained, and Rare Drop Rate, up to a bonus of +10%.

You do not need to be a specific class to benefit from an Add-on Skill!

tl;dr

If you just want to put a few levels in all of them quickly before maxing them out, a subjective priority of unlock would be this order:

1. Bouncer (To be able to regenerate PP while using the Photon Dash/Glide)
2. Braver (Increase to passive Critical Hit Rate, essential for higher level weapons)
3. Fighter (Increase to Critical Hit damage, affects all classes)
4. Hunter, Ranger, or Force, depending on main weapon
5. Slayer (Increases Critical Hit rate against stunned enemies)
6. Gunner (Boosts on-hit Photon Blast build rate)
7. Techter (Boosts passive Photon Blast build rate)
8. Waker (Boosts maximum PP, lowest priority)

The most important immediate boosts to reroll for with higher rank generation methods are arguably Slayer to use your Photon Blast more often, Ranger to deal more damage with your Photon Blast, and Techter to gain extra HP and damage resist. Others are more conditional. Further information or detailed reroll information is below.

Generation

Every Add-on Skill will generate with a Main Effect and two Sub Effects. The Main Effect will always occur when generating an Add-on Skill, while the two Sub Effects will be randomly chosen.

Once you unlock a specific level in the Main Effect, that will be the lowest level it can roll at. However, Sub Effects can roll at any level, depending on the generation type used.

Add-on Skills by class

Common Sub-Effects

Many Sub-Effects appear on multiple classes. For brevity's sake, they are listed first. Recovery and HP up will be omitted from future class listings, while Status Resistance will be listed so you know which status resist is granted.

HP Recovery upon Joining Trial (HU, RA, FO, BR, WA)
When a Trial begins, you will automatically restore a portion of your maximum HP. Each HP Recovery upon Joining Trial effect set stacks, and the total sum of HP Recovery effects is how much you will recover, rounded down to the nearest whole HP. As an example, If you have a lv20, lv10, and lv10 set, your total heal will be 50% of maximum HP, but if you have 1,265 HP, the heal will be rounded down to 632 instead of rounded up to 633. Judgement for "joining a trial" is any instance where you are on the map when an event that would cause a "Trial Joined" Auto Chat to play, so this effect will also trigger if you are in an exploration zone when a Gigantix spawns, when an Ancient boss spawns, or when a Tyrant Halvaldi Vera spawns. If the Trial is already active and you enter the map, this effect will not occur.
Lv1	Lv2	Lv3	Lv4	Lv5	Lv6	Lv7	Lv8	Lv9	Lv10
-	-	-	-	-	-	-	-	-	15%
Lv11	Lv12	Lv13	Lv14	Lv15	Lv16	Lv17	Lv18	Lv19	Lv20
-	-	-	-	-	-	-	-	-	20%
PP Recovery upon Joining Trial (FI, GU, TE, BO, SL)
When a Trial begins, you will automatically restore a portion of your maximum PP. Each PP Recovery upon Joining Trial effect set stacks, and the total sum of PP Recovery effects is how much you will recover. Due to game mechanics, decimal PP exists, so the recovered amount can vary. Judgement for "joining a trial" is any instance where you are on the map when an event that would cause a "Trial Joined" Auto Chat to play, so this effect will also trigger if you are in an exploration zone when a Gigantix spawns, when an Ancient boss spawns, or when a Tyrant Halvaldi Vera spawns. If the Trial is already active and you enter the map, this effect will not occur.
Lv1	Lv2	Lv3	Lv4	Lv5	Lv6	Lv7	Lv8	Lv9	Lv10
-	-	-	-	-	-	-	-	-	-
Lv11	Lv12	Lv13	Lv14	Lv15	Lv16	Lv17	Lv18	Lv19	Lv20
-	-	-	-	-	-	-	-	-	-
HP Up (All classes)
Increases your maximum base HP. This is applied before boosts such as Quick Food or Alliance Mag, and each HP Up effect from each class stacks with each other, allowing you to gain a large amount of extra HP which can make otherwise dangerous attacks easier to withstand.
Lv1	Lv2	Lv3	Lv4	Lv5	Lv6	Lv7	Lv8	Lv9	Lv10
-	-	-	-	-	-	-	-	-	-
Lv11	Lv12	Lv13	Lv14	Lv15	Lv16	Lv17	Lv18	Lv19	Lv20
-	-	-	-	-	-	-	-	-	-
Status Resist Up (All classes)
Increases status resistance, allowing you to take more damage from specific elemental attribute attacks without suffering from their status. Each class has a specific Status Resist Up, while some Status Resists are repeated between classes. In these cases, the effects stack. For brevity's sake, this is the only part of the page where level effects will be listed.
Lv1	Lv2	Lv3	Lv4	Lv5	Lv6	Lv7	Lv8	Lv9	Lv10
-	-	-	-	-	-	-	-	-	-
Lv11	Lv12	Lv13	Lv14	Lv15	Lv16	Lv17	Lv18	Lv19	Lv20
-	-	-	-	-	-	-	-	-	-

Hunter

Main effect: Melee Weapon Potency Up
Increases damage dealt with Swords, Wire Lances, Spears, Twin Daggers, Double Sabers, Knuckles, Katanas, and Soaring Blades.
Lv1	Lv2	Lv3	Lv4	Lv5	Lv6	Lv7	Lv8	Lv9	Lv10
-	-	-	-	-	-	-	-	-	-
Lv11	Lv12	Lv13	Lv14	Lv15	Lv16	Lv17	Lv18	Lv19	Lv20
-	-	-	-	-	-	-	-	-	-
Sub effect: PA Charge Movement Speed Up
Increases movement speed while charging Photon Arts. Does not apply while charging Techniques or normal attacks.
Lv1	Lv2	Lv3	Lv4	Lv5	Lv6	Lv7	Lv8	Lv9	Lv10
-	-	-	-	-	-	-	-	-	-
Lv11	Lv12	Lv13	Lv14	Lv15	Lv16	Lv17	Lv18	Lv19	Lv20
-	-	-	-	-	-	-	-	-	-
Sub effect: Burn Resistance Up (HU)
Increases resistance to the Burn status. Stacks with Braver's Burn Resistance Up.