Elemental Resistance (Passive) 
elemental attacks will do less damage to u. however, note that not all magical attacks are elemental. at max level, it reduces 40% of the magical damage which is quite significant.
Crusher (Spear) (Active) only works with a spear. always stabs, doing stable and high damage to up to 3 monters at a time. spear and hybrid DKs must have this skill.
Crusher (Pole arm) (Active) 
always stabs and only works with a polearm. useless skill. fury does more dmg and has a better range. DO NOT learn this, u will be doing pathetic damage with this.
Dragon Fury (Spear) (Active) 
always swings, doing low damage since a spear is used. however, its range is huge, between 1/3 to 1/2 of the screen, can be used to lure monsters.
Dragon Fury (Pole arm) (Active) always swings, doing stable and quite high (higher than power strike but lower than most 3rd job skills) damage with a polearm. its has huge range and can attack up to 6 monsters. it is rather fast, unlike crusher which is slow. Polearm DK's main attack.
Sacrifice (Active) an attack which ignores enemy weapon def but sacrifices HP. damage is unstable due to the stab/swing motion and u will sacrifice alot of ur HP using this skill and the damage does not necessarily be higher than spear crusher. not practical without a cleric.
Dragon Roar (Active) an attack which can hit up to 15 monsters. at max lvl, it can reach the whole screen. however, it stuns the user and uses a large amout of HP to cast. u will need a cleric to heal u if u want to use it regularly.
Power Crash (Support) cancels monsters power up skill. not sure if it is needed for zakum, but its useless for normal monsters. theres is no need to cancel monsters power up skills since they will die in afew hits and if there is a need to do so, priests have dispel which can do that.
Dragon Blood (Support) additional 12 attack at maxed lvl at the cost of 20 hp every 4 seconds. 12 attack will give a huge damage boost and 800hp for 160 seconds is about 800 meso for the duration. definately learn this.
- skills that you should seriously consider learning - skills that are optional but good to have - skills that are of no useSp Builds
Hybrid DK
Crusher 1st build
Spear Crusher 30(max)
Spear Fury 1
Elemental Resistance 1
Dragon Blood 20(max)
Elemental Resistance 10
Polearm Fury 30(max)
Elemental Resistance 20(max)
Sacrifice 3
Dragon Roar 30(max)
17sp into Sacrifice or Power Crush or Spear Fury or Booster
total: 151sp
this build learns crusher 1st, which is better for bigger & stronger monsters. crusher will be the main attack.
Fury 1st build
Polearm Fury 30(max)
Elemental Resistance 1
Dragon Blood 20(max)
Spear Crusher 30(max)
Spear Fury 1
Elemental Resistance 20(max)
Sacrifice 3
Dragon Roar 30(max)
17sp into Sacrifice or Power Crush or Spear Fury or Booster
total: 151sp
this build is better for training at weaker monsters where u can 1-2hit kill. it will work better than getting crusher 1st at 7x in most maps.
Lv10/20 fury build
Polearm Fury 10/20
Spear Crusher 30(max)
Elemental Resistance 1
Spear Fury 1
Dragon Blood 20(max)
Elemental Resistance 20(max)
Polearm Fury 30(max)
Sacrifice 3
Dragon Roar 30(max)
17sp into Sacrifice or Power Crush or Spear Fury or Booster
total: 151sp
this build uses fury to train in 7x on weaker monsters, then use crusher once it is near maxed for the bigger monsters.
Spear DK
Spear Crusher 30(max)
Elemental Resistance 1
Spear Fury 1
Dragon Blood 20(max)
Elemental Resistance 20(max)
Sacrifice 3
Dragon Roar 30(max)
Spear Fury 30(max)
17sp into Sacrifice or Power Crush
total: 151sp
if u dont like Spear fury, learn the other 2 skills.
Polearm DK
Polearm Fury 30(max)
Elemental Resistance 1
Dragon Blood 20(max)
Elemental Resistance 10
Sacrifice 30(max)
Elemental Resistance 20(max)
Dragon Roar 30(max)
Power Crush 20(max)
total: 151sp
Polearm > Hybrid
this basically means that u only convert to hybrid in 3rd job. Polearm users might consider this as Polearm Fury is weak vs 1 monster while sacrifice is too costly vs 1 monster.
Polearm Fury 30(max)
Dragon Blood 20(max)
Elemental Resistance 1
Spear Mastery 19
Spear Booster 6-10
Spear Crusher 30(max)
Spear Fury 1
Elemental Resistance 20(max)
rest of the points into anything
total: 151sp
the skills that u MUST learn are: 30 Polearm Fury, 20 Dragon Blood, 19 Spear Mastery(60% mastery), 30 Spear Crusher, Spear Booster. the others are less important.
FAQ:
1. Spear crusher or polearm fury which 1 to learn 1st for hybrids.
it depends on where u want to train, fury is faster at places like zombies, dmt, sanc2 when u can kill them below 2hits, while crusher does better at bigger monsters. basically, fury trains in places with big spawn of weaker mobs while crusher trains on bigger mobs.
2. Sacrifice?
other than pure polearm DKs, others do not need to max sacrifice. Polearm DKs need this skill as they lack of a strong 1 on 1 skill. for others, this skill is useless as there is spear buster. spear crusher does more stable and higher dmg even to monsters with high weapon defense. Add in the fact that sacrifice cannot be used against bosses and the user absorbs dmg, sacrifice is 1 of the skill u do not need to learn.
3. Elemental resistance?
elemental resistance reduce the damage u take from elemental attacks (lucida, bain..). at lv1 it has 12%, increases by 2% per lv until lv10 then 1% every lv after that. it will save u lots of potion as priest will not have time to heal 24/7 unless in a 2 person party (they will be going around giving HS to other party members). definitely a skill to max since u have more than enough skill points. get 1 point in it as early as possible. if u do not have enough skill points for whatever reasons, try to get it to lv10.
4. Spear fury?
fury has a greater range than buster, thus able to lure mobs and gather them. it is good a have at least lv1 on it. it is also a good skill to learn as buster usually overkills small monsters. with fury, u will have another skill which can kill small mobs quite fast. or in some occasions instead of doing 2 buster, 1 buster + 1 fury is enough to kill off monsters. consider getting it to 20/30 if u have enough skill points.
5. Is it a gd idea to max dragon roar and find a cleric to train with roar?
i do not recommend it as u probably need to roar a few times to kill off monsters. theres also a lack of location where there is a constant spawn of 15 (or close to 15) monsters. u will also piss other ppl off ksing their monsters. it also uses too much hp, u will need a cleric with u if u want to cast it constantly.
6. Spear fury vs Sacrifice.
personally, i prefer spear fury, since most of the time, we will be using crusher, fury can lure mobs or act as a finisher.