After many hours of slaving at a Builder program ive comeup with the following ranged/melee build for a Crab Spider. Since i love how they seem to act as NPCs i wanted my Crab to be similar so there are a few powers that were must haves, like supression for example. Anyway take a look and let me know what you think  
 Villain Plan by Mids' Villain Designer 1.30
http://www.honourableunited.org.uk/mhd.php
The Ultimate Crab Spider Build: Level 50 Natural Crab Spider
Primary Power Set: Crab Soldier
Secondary Power Set: Crab Training
Power Pool: Fitness
Power Pool: Leaping
Ancillary Pool: Mace Mastery
Villain Profile:
Level 1: Slice
Villain Plan by Mids' Villain Designer 1.30
http://www.honourableunited.org.uk/mhd.php
The Ultimate Crab Spider Build: Level 50 Natural Crab Spider
Primary Power Set: Crab Soldier
Secondary Power Set: Crab Training
Power Pool: Fitness
Power Pool: Leaping
Ancillary Pool: Mace Mastery
Villain Profile:
Level 1: Slice <ul type="square">[*] (A) 
Accuracy IO: Level 50[*] (3) 
Accuracy IO: Level 50[*] (3) 
Damage Increase IO: Level 50[*] (7) 
Damage Increase IO: Level 50[*] (19) 
Touch of Lady Grey - Chance for Negative Damage: Level 50[*] (21) 
Damage Increase IO: Level 20[/list]
Level 1: Wolf Spider Armor <ul type="square">[*] (A) 
Resist Damage IO: Level 50[/list]
Level 2: Longfang <ul type="square">[*] (A) 
Devastation - Accuracy/Damage: Level 50[*] (5) 
Devastation - Damage/Endurance: Level 50[*] (5) 
Devastation - Damage/Recharge: Level 50[*] (7) 
Devastation - Accuracy/Damage/Recharge: Level 50[*] (19) 
Touch of Lady Grey - Chance for Negative Damage: Level 50[*] (21) 
Devastation - Accuracy/Damage/Endurance/Recharge: Level 30[/list]
Level 4: Crab Spider Armor Upgrade <ul type="square">[*] (A) 
Steadfast Protection - Knockback Protection: Level 30[*] (17) 
Resist Damage IO: Level 50[/list]
Level 6: Swift <ul type="square">[*] (A) 
Run Speed IO: Level 50[/list]
Level 8: Suppression <ul type="square">[*] (A) 
Positron's Blast - Accuracy/Damage: Level 50[*] (9) 
Positron's Blast - Damage/Endurance: Level 50[*] (9) 
Positron's Blast - Damage/Recharge: Level 50[*] (13) 
Positron's Blast - Accuracy/Damage/Endurance: Level 50[*] (13) 
Positron's Blast - Chance of Damage(Energy): Level 50[*] (15) 
Endurance Reduction IO: Level 50[/list]
Level 10: Tactical Training: Maneuvers <ul type="square">[*] (A) 
Luck of the Gambler - Defense/Endurance/Recharge: Level 50[*] (11) 
Luck of the Gambler - Defense: Level 50[*] (11) 
Luck of the Gambler - Defense/Endurance: Level 50[*] (17) 
Karma - Knockback Protection: Level 30[/list]
Level 12: Combat Jumping <ul type="square">[*] (A) 
Karma - Knockback Protection: Level 30[/list]
Level 14: Health <ul type="square">[*] (A) 
Numina's Convalescence - +Regeneration/+Recovery: Level 50[*] (15) 
Numina's Convalescence - Heal: Level 50[/list]
Level 16: Tactical Training: Assault <ul type="square">[*] (A) 
Endurance Reduction IO: Level 50[/list]
Level 18: Super Jump <ul type="square">[*] (A) 
Unbounded Leap - +Stealth: Level 50[/list]
Level 20: Venom Grenade <ul type="square">[*] (A) 
Positron's Blast - Chance of Damage(Energy): Level 50[*] (31) 
Positron's Blast - Accuracy/Damage: Level 50[*] (33) 
Positron's Blast - Damage/Endurance: Level 50[/list]
Level 22: Stamina <ul type="square">[*] (A) 
Endurance Modification IO: Level 50[*] (23) 
Endurance Modification IO: Level 50[*] (23) 
Endurance Modification IO: Level 50[/list]
Level 24: Arm Lash <ul type="square">[*] (A) 
Scirocco's Dervish - Accuracy/Damage: Level 50[*] (25) 
Scirocco's Dervish - Damage/Recharge: Level 50[*] (25) 
Scirocco's Dervish - Accuracy/Recharge: Level 50[*] (46) 
Scirocco's Dervish - Chance of Damage(Lethal): Level 50[*] (46) 
Touch of Lady Grey - Chance for Negative Damage: Level 50[*] (46) 
Scirocco's Dervish - Accuracy/Damage/Endurance: Level 50[/list]
Level 26: Frenzy <ul type="square">[*] (A) 
Armageddon - Damage: Level 50[*] (27) 
Armageddon - Damage/Recharge: Level 50[*] (27) 
Armageddon - Accuracy/Damage/Recharge: Level 50[*] (40) 
Armageddon - Chance for Fire Damage: Level 50[*] (42) 
Touch of Lady Grey - Chance for Negative Damage: Level 50[*] (43) 
Armageddon - Damage/Endurance: Level 50[/list]
Level 28: Fortification <ul type="square">[*] (A) 
Resist Damage IO: Level 50[*] (29) 
Titanium Coating - Endurance: Level 50[*] (29) 
Titanium Coating - Resistance: Level 50[*] (43) 
Titanium Coating - Resistance/Endurance: Level 50[/list]
Level 30: Serum <ul type="square">[*] (A) 
Numina's Convalescence - Heal/Recharge: Level 50[*] (31) 
Numina's Convalescence - Heal: Level 50[*] (31) 
Numina's Convalescence - Heal/Endurance/Recharge: Level 50[*] (37) 
Healing IO: Level 50[*] (43) 
Recharge Reduction IO: Level 50[*] (45) 
Recharge Reduction IO: Level 50[/list]
Level 32: Omega Maneuver <ul type="square">[*] (A) 
Accuracy IO: Level 50[*] (33) 
Accuracy IO: Level 50[*] (33) 
Damage Increase IO: Level 50[*] (34) 
Damage Increase IO: Level 50[*] (34) 
Damage Increase IO: Level 50[*] (34) 
Recharge Reduction IO: Level 50[/list]
Level 35: Summon Spiderlings <ul type="square">[*] (A) 
Recharge Reduction IO: Level 40[*] (36) 
Recharge Reduction IO: Level 40[*] (36) 
Recharge Reduction IO: Level 40[*] (36) 
Edict of the Master - Accuracy/Damage: Level 40[*] (37) 
Edict of the Master - Defense Bonus: Level 40[*] (37) 
Edict of the Master - Damage: Level 40[/list]
Level 38: Call ReinForcements <ul type="square">[*] (A) 
Recharge Reduction IO: Level 50[*] (39) 
Recharge Reduction IO: Level 50[*] (39) 
Recharge Reduction IO: Level 50[*] (39) 
Soulbound Allegiance - Damage: Level 50[*] (40) 
Soulbound Allegiance - Damage/Recharge: Level 50[*] (40) 
Soulbound Allegiance - Accuracy/Damage/Recharge: Level 50[/list]
Level 41: Web Envelope <ul type="square">[*] (A) 
Enfeebled Operation - Accuracy/Recharge: Level 50[*] (42) 
Enfeebled Operation - Endurance/Immobilize: Level 50[*] (42) 
Enfeebled Operation - Accuracy/Immobilize: Level 50[/list]
Level 44: Disruptor Blast <ul type="square">[*] (A) 
Positron's Blast - Accuracy/Damage: Level 50[*] (45) 
Positron's Blast - Damage/Recharge: Level 50[*] (45) 
Positron's Blast - Chance of Damage(Energy): Level 50[*] (50) 
Positron's Blast - Accuracy/Damage/Endurance: Level 50[/list]
Level 47: Summon Blaster <ul type="square">[*] (A) 
Recharge Reduction IO: Level 50[*] (48) 
Recharge Reduction IO: Level 50[*] (48) 
Recharge Reduction IO: Level 50[*] (48) 
Sovereign Right - Accuracy/Damage: Level 50[*] (50) 
Sovereign Right - Damage/Endurance: Level 50[*] (50) 
Sovereign Right - Accuracy/Damage/Endurance: Level 50[/list]
Level 49: Mental Training <ul type="square">[*] (A) 
Run Speed IO: Level 50[/list]
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Level 1: Brawl <ul type="square">[*] (A) 
Accuracy IO: Level 50[/list]
Level 1: Sprint <ul type="square">[*] (A) 
Run Speed IO: Level 50[/list]
Level 2: Rest <ul type="square">[*] (A) 
Recharge Reduction IO: Level 50[/list]
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[u]Set Bonus Totals:[u]<ul type="square">[*]+3% DamageBuff[*]+3.13% Defense(AoE)[*]+42% Enhancement(Accuracy)[*]+3% Enhancement(Immobilize)[*]+16.3% Enhancement(RechargeTime)[*]+135.6 (11.3%) HitPoints[*]+4% JumpSpeed[*]+Knockback (Mag -12)[*]+MezResist(Confused) (Mag 2.75%)[*]+MezResist(Held) (Mag 3.3%)[*]+MezResist(Sleep) (Mag 4.95%)[*]+11.5% Recovery[*]+72% Regeneration[*]+7.25% Resistance(Fire)[*]+7.25% Resistance(Cold)[*]+5% Resistance(Negative)[*]+PBAoE (20ft) Pet +Def(All) 5%[/list]
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[u]Set Bonuses:[u]
[u]Devastation[u]
(Longfang)<ul type="square">[*]  +12% Regeneration[*]  +27.1 (2.25%) HitPoints[*]  +3% DamageBuff[*]  +MezResist(Held) (Mag 3.3%)[/list]
[u]Steadfast Protection[u]
(Crab Spider Armor Upgrade)<ul type="square">[*]
  +Knockback (Mag -4)[/list]
[u]Positron's Blast[u]
(Suppression)<ul type="square">[*]  +2.5% Recovery[*]  +1.575% Res(Fire, Cold)[*]  +9% Enhancement(Accuracy)[*]  +6.25% Enhancement(RechargeTime)[/list]
[u]Luck of the Gambler[u]
(Tactical Training: Maneuvers)<ul type="square">[*]  +10% Regeneration[*]  +13.6 (1.13%) HitPoints[/list]
[u]Karma[u]
(Tactical Training: Maneuvers)<ul type="square">[*]
  +Knockback (Mag -4)[/list]
[u]Karma[u]
(Combat Jumping)<ul type="square">[*]
  +Knockback (Mag -4)[/list]
[u]Numina's Convalescence[u]
(Health)<ul type="square">[*]  +12% Regeneration[/list]
[u]Positron's Blast[u]
(Venom Grenade)<ul type="square">[*]  +2.5% Recovery[*]  +1.575% Res(Fire, Cold)[/list]
[u]Scirocco's Dervish[u]
(Arm Lash)<ul type="square">[*]  +10% Regeneration[*]  +3.13% Resistance(Negative)[*]  +9% Enhancement(Accuracy)[*]  +3.13% Defense(AoE)[/list]
[u]Armageddon[u]
(Frenzy)<ul type="square">[*]  +4% Recovery[*]  +2.52% Res(Fire, Cold)[*]  +15% Enhancement(Accuracy)[*]  +10% Enhancement(RechargeTime)[/list]
[u]Titanium Coating[u]
(Fortification)<ul type="square">[*]  +MezResist(Sleep) (Mag 2.2%)[*]  +18.1 (1.5%) HitPoints[/list]
[u]Numina's Convalescence[u]
(Serum)<ul type="square">[*]  +12% Regeneration[*]  +22.6 (1.88%) HitPoints[/list]
[u]Edict of the Master[u]
(Summon Spiderlings)<ul type="square">[*]  +4% JumpSpeed[*]  +18.1 (1.5%) HitPoints[*]
  +PBAoE (20ft) Pet +Def(All) 5%[/list]
[u]Soulbound Allegiance[u]
(Call ReinForcements)<ul type="square">[*]  +16% Regeneration[*]  +36.2 (3%) HitPoints[/list]
[u]Enfeebled Operation[u]
(Web Envelope)<ul type="square">[*]  +3% Enhancement(Immobilize)[*]  +1.88% Resistance(Negative)[/list]
[u]Positron's Blast[u]
(Disruptor Blast)<ul type="square">[*]  +2.5% Recovery[*]  +1.575% Res(Fire, Cold)[*]  +9% Enhancement(Accuracy)[/list]
[u]Sovereign Right[u]
(Summon Blaster)<ul type="square">[*]  +MezResist(Sleep) (Mag 2.75%)[*]  +MezResist(Confused) (Mag 2.75%)[/list]
P.S. i knw the slotting is a bit wishful thinking but its something to really play towards i think as it will fill alot of the gaps.