Upon changing into 4th Job, you are introduced to two new mechanics: Activity Point and Trait Stats.

Activity Point (AP) is a new resource mechanic exclusive to 4th job skills.

• Some 4th job skills grant AP. You can check the skill's description
• There are usually two “ultimate” skills that consumes majority of your AP
• The maximum amount of AP you can hold is 200 regardless of class.
• Currently only one method exists to get AP faster via Elemental Master's Increasing Activity
• Elemental Master's Activity Burn can remove AP from an enemy.
• When you die or enter a PVP or WOE map, you lose all your AP.

There are 6 main trait stats that a player can allocate towards: POW, STA, WIS, SPL, CON and CRT.
Each of these main trait stats can grant various sub-trait stats: P.ATK, S.MATK, RES, MRES, H.PLUS, and C.RATE.
Any levels from 200 and beyond will grant Trait Stats instead of the normal Primary Stats.

• Every level gives 3 trait stat points.
• If a level is divisible by 5 (Ex: 200, 205, 210…), you will get 7 trait stat points.
• When you change to 4th job, you will get 7 trait stat points because level 200 is divisible by 5.

Trait that increases status physical attack and Power Attack (P.ATK)

• Status physical attack increases by 5 per 1 point.
• P.ATK increases by 1 per 3 points.

Trait that increases physical resistance (RES)

• RES increases by 1 per 1 point.
• RES increases by 5 per 3 points.

Trait that increases magic resistance (MRES)

• MRES increases by 1 per 1 point.
• MRES increases by 5 per 3 points.

Trait that increases status magic attack and Spell Magic Attack (S.MATK)

• Status Magic Attack increases by 5 per 1 point.
• S.MATK increases by 1 per 3 points.

Trait that increases accuracy (HIT), evasion (FLEE), Power Attack (P.ATK) and Spell Magic Attack (S.MATK)

• HIT increases by 2 per 1 point.
• FLEE increases by 2 per 1 point.
• P.ATK increases by 1 per 5 points.
• S.MATK increases by 1 per 5 points.

Trait that increases Heal Plus (H.PLUS) and Critical Rate (C.RATE)

• H.PLUS increases by 1 per 1 point.
• C.RATE increases by 1 per 3 points.

Final status physical attack and final equipment attack increases by %.

Final status magic attack and final equipment magic attack increases by %.

Before calculating physical defense, it reduces normal physical damage taken by %. (Only up to 50%)

Physical Damage % Received will be equal to (2000+RES)/(2000+5*RES)

Before calculating the magic defense, it reduces the normal magic damage received by %. (Only up to 50%)

MAgical Damage % Received will be equal to (2000+MRES)/(2000+5*MRES)

Increases the final heal recovery by %. This increase is applied after normal heal recovery increasing effects.

Increases the critical damage percent by %.

• At 0 C.RATE, your critical damage is 140%.
• At 10 C.RATE, your critical damage increases from 140% to 150%.

Sources:
https://ro.gnjoy.com/event/2020/09/0909_ro1_4thOccupation_final/