PVP/PK
Force Kick (FK) - lvl 9 or 12... no higher or it's cool down (C.D.) will screw up combo.
Force Assault (FA) - lvl 20... it's what is considered a filler/fast skill as the C.D. is rather quick when doing combo.
Force Slash (FS) - lvl 20... it's what is considered a filler/fast skill as the C.D. is rather quick when doing combo.
Assassinate (Ass) - Personal pref*... considered a finishing move since it's C.D. can be slow or fast depending on lvl.
Infernal Impact (II) - Personal pref*... considered a finishing move since it's C.D. can be slow or fast depending on lvl.
Seal of Damnation (SoD) - Personal pref*... considered a finishing move since it's C.D. can be slow or fast depending on lvl.
Abyssal Crystal (AC) - lvl 20... This is only if your other skills do not kill your oppenent and is used rarely if at all.
Debuffs that are quite useful in PK ONLY are Hard Luck (HL), Execration (Root), Lower Defense (def down), Field of Enervation (lvl down), Mana Freeze (mf). It's an unwritten rule of sorts that debuffs are not allowed in PVP unless you're doing what is called a freestyle pvp.
PVE
You will find I do a very 'odd' PVE combo for FB... I've found that this one works for me... it may not nessacerily work for you and I will add a move that MOST FB's do use when hitting monsters/bosses.
Force Kick (FK) - lvl 9 or 12... no higher or it's cool down (C.D.) will screw up combo.
Force Drive (FD) - lvl 20... it's what is considered a filler/fast skill as the C.D. is rather quick when doing combo.
Force Assault (FA) - lvl 20... it's what is considered a filler/fast skill as the C.D. is rather quick when doing combo.
Assassinate (Ass) - Personal pref*... considered a finishing move since it's C.D. can be slow or fast depending on lvl.
Infernal Impact (II) - Personal pref*... considered a finishing move since it's C.D. can be slow or fast depending on lvl.
Seal of Damnation (SoD) - Personal pref*... considered a finishing move since it's C.D. can be slow or fast depending on lvl.
Abyssal Crystal (AC) - lvl 20... This is only if your other skills do not kill your oppenent and is used rarely if at all.
Force Impact (FI) - lvl 9... This is rarely used as the skill casting time is extremely slow use sparingly if at all.
Infernal Stigma (IS) - lvl 9... This move has a semi slow casting time use somewhere in the middle before your finishers but after quick skills.**
*Personal Pref means that it can be set anywhere from lvl 9 to lvl 20... depending on YOUR playing style and set up.
** I do not use nor have this skill... I know MANY FB's that do but I personally have found it gets in the way of my other skills and have not found any true advantages to using it, it's a personal preference as to whether YOU use it or not.