Take it with a grain of salt, it has been a while.
In general you are looking for breakpoints on attack speed and faster hit recovery.
For sustain you want "life after kill", that's the only thing that works properly.
stats: str/dex for gear, everything else vit
skills: Blink 1pt; shadow refuge 1pt, shadow rush (1-6 depending on how fast u wanna walk/run) perfect being 1pt (max later), 1 Queen of blades
Way of the Spider, Scorpion Blade, Lethal Incision all max, not sure what the exact order is (u can respec until lvl 50 for free, just try it.)
Weapon:
Death Touch

Death Touch
Throwing Knife (4)
Throw Damage: 1 to 4
One-Hand Damage: 2 to 4
Required Level: 1
Required Dexterity: 17
Item Level: 1
Dexterity Damage Bonus: (0.11 per Dexterity)%
2% Chance to cast level 8 Scorpion Blade on Kill
+1 to Assassin Skill Levels
(21 to 50)% Bonus to Attack Rating
+(6 to 8)% to Poison Spell Damage
-(6 to 8)% to Enemy Poison Resistance
Requirements +15%
Socketed (1)
Throw Damage: 7 to 8
One-Hand Damage: 5 to 6
Required Level: 18
Required Dexterity: 45
Item Level: 20
Dexterity Damage Bonus: (0.11 per Dexterity)%
3% Chance to cast level 16 Scorpion Blade on Kill
+2 to Assassin Skill Levels
(81 to 110)% Bonus to Attack Rating
+(11 to 13)% to Poison Spell Damage
-(11 to 13)% to Enemy Poison Resistance
Requirements +25%
Socketed (2)
Throw Damage: 17 to 18
One-Hand Damage: 12
Required Level: 36
Required Dexterity: 109
Item Level: 40
Dexterity Damage Bonus: (0.11 per Dexterity)%
5% Chance to cast level 24 Scorpion Blade on Kill
+3 to Assassin Skill Levels
(141 to 170)% Bonus to Attack Rating
+(16 to 18)% to Poison Spell Damage
-(16 to 18)% to Enemy Poison Resistance
Requirements +35%
Socketed (2)
Throw Damage: 22 to 23
One-Hand Damage: 14
Required Level: 45
Required Dexterity: 250
Item Level: 72
Dexterity Damage Bonus: (0.11 per Dexterity)%
6% Chance to cast level 32 Scorpion Blade on Kill
+(4 to 5) to Assassin Skill Levels
(171 to 200)% Bonus to Attack Rating
+(18 to 20)% to Poison Spell Damage
-(18 to 20)% to Enemy Poison Resistance
Requirements +50%
Socketed (2)
Shield:
Destroying Angel

Destroying Angel
Small Shield (4)
Defense: (59 - 65) to (112 - 123)
Chance to Block: Class%
Required Level: 2
Required Strength: 27
Required Dexterity: 34
Item Level: 4
+50 Poison Damage over 2 seconds
+(6 to 10)% to Poison Spell Damage
-3% to Enemy Poison Resistance
Attacker Flees after Striking (4 to 5)%
+(12 to 23)% Enhanced Defense
Poison Resist +(21 to 25)%
Requirements +10%
Socketed (1)
Defense: (229 - 248) to (363 - 392)
Chance to Block: Class%
Required Level: 20
Required Strength: 60
Required Dexterity: 55
Item Level: 23
+150 Poison Damage over 2 seconds
+(16 to 20)% to Poison Spell Damage
-6% to Enemy Poison Resistance
Attacker Flees after Striking (8 to 9)%
+(35 to 46)% Enhanced Defense
Poison Resist +(31 to 35)%
Requirements +20%
Socketed (3)
Defense: (581 - 621) to (880 - 941)
Chance to Block: Class%
Required Level: 37
Required Strength: 227
Required Dexterity: 124
Item Level: 43
+300 Poison Damage over 2 seconds
+(26 to 30)% to Poison Spell Damage
-9% to Enemy Poison Resistance
Attacker Flees after Striking (12 to 15)%
+(58 to 69)% Enhanced Defense
Poison Resist +(41 to 45)%
Requirements +30%
Socketed (4)
Defense: (858 - 914) to (1287 - 1371)
Chance to Block: Class%
Required Level: 46
Required Strength: 490
Required Dexterity: 278
Item Level: 77
+600 Poison Damage over 2 seconds
+(36 to 40)% to Poison Spell Damage
-12% to Enemy Poison Resistance
Attacker Flees after Striking (16 to 20)%
+(69 to 80)% Enhanced Defense
Poison Resist +(46 to 50)%
Requirements +40%
Socketed (4)
Body armor:
Queen of Glass

Queen of Glass
Ancient Armor (4)
Defense: (315 - 344) to (630 - 688)
Required Level: 11
Required Strength: 33 to 34
Item Level: 19
15% Cast Speed
-(6 to 8)% to Enemy Elemental Resistances
+(18 to 29)% Enhanced Defense
+(76 to 125) to Mana
Lightning Resist +(21 to 25)%
Cold Resist +(21 to 25)%
Requirements -(11 to 15)%
Socketed (2)
Defense: (899 - 969) to (1718 - 1852)
Required Level: 30
Required Strength: 57 to 60
Item Level: 34
25% Cast Speed
-(11 to 13)% to Enemy Elemental Resistances
+(41 to 52)% Enhanced Defense
+(176 to 225) to Mana
Lightning Resist +(31 to 35)%
Cold Resist +(31 to 35)%
Requirements -(21 to 25)%
Socketed (4)
Defense: (2084 - 2224) to (3911 - 4173)
Required Level: 47
Required Strength: 175 to 186
Item Level: 55
35% Cast Speed
-(16 to 18)% to Enemy Elemental Resistances
+(64 to 75)% Enhanced Defense
+(276 to 325) to Mana
Lightning Resist +(41 to 45)%
Cold Resist +(41 to 45)%
Requirements -(31 to 35)%
Socketed (5)
Defense: (3013 - 3202) to (5650 - 6005)
Required Level: 54
Required Strength: 323 to 344
Item Level: 90
40% Cast Speed
-(18 to 20)% to Enemy Elemental Resistances
+(75 to 86)% Enhanced Defense
+(326 to 375) to Mana
Lightning Resist +(46 to 50)%
Cold Resist +(46 to 50)%
Requirements -(36 to 40)%
Socketed (6)
or
Acidblood

Acidblood
Leather Armor (4)
Defense: (43 - 50) to (86 - 101)
Required Level: 2
Required Strength: 27
Item Level: 3
-3% to Enemy Poison Resistance
+(11 to 15)% to Summoned Minion Life
+(11 to 30)% Enhanced Defense
Fire Resist +(11 to 15)%
Poison Resist +(11 to 15)%
+(11 to 15) Life after each Kill
Socketed (2)
Defense: (198 - 225) to (322 - 366)
Required Level: 18
Required Strength: 53
Item Level: 21
-6% to Enemy Poison Resistance
+(21 to 25)% to Summoned Minion Life
+(41 to 60)% Enhanced Defense
Fire Resist +(21 to 25)%
Poison Resist +(21 to 25)%
+(16 to 20) Life after each Kill
Socketed (4)
Defense: (530 - 589) to (815 - 906)
Required Level: 35
Required Strength: 184
Item Level: 41
-9% to Enemy Poison Resistance
+(31 to 35)% to Summoned Minion Life
+(71 to 90)% Enhanced Defense
Fire Resist +(31 to 35)%
Poison Resist +(31 to 35)%
+(21 to 25) Life after each Kill
Socketed (5)
Defense: (858 - 982) to (1312 - 1501)
Required Level: 45
Required Strength: 368
Item Level: 75
-12% to Enemy Poison Resistance
+(36 to 40)% to Summoned Minion Life
+(101 to 130)% Enhanced Defense
Fire Resist +(36 to 40)%
Poison Resist +(36 to 40)%
+(26 to 30) Life after each Kill
Socketed (6)
Boots: honorifc or
Rabbit's Foot
Rabbit's Foot
Boots (4)
Defense: 8 to 14
Required Level: 1
Required Strength: 21
Item Level: 1
(10 to 40)% Movement Speed
+10% to Spell Damage
+5 Maximum Stamina
(1 to 5)% Gold Find
(1 to 5)% Magic Find
Requirements -15%
Socketed (1)
Defense: 75 to 88
Required Level: 17
Required Strength: 35
Item Level: 20
(10 to 40)% Movement Speed
+12% to Spell Damage
+10 Maximum Stamina
(5 to 10)% Gold Find
(5 to 10)% Magic Find
Requirements -30%
Socketed (2)
Defense: 184 to 215
Required Level: 34
Required Strength: 96
Item Level: 40
(10 to 40)% Movement Speed
+16% to Spell Damage
+15 Maximum Stamina
(15 to 20)% Gold Find
(15 to 20)% Magic Find
Requirements -45%
Socketed (3)
Defense: 258 to 296
Required Level: 43
Required Strength: 140
Item Level: 71
(10 to 40)% Movement Speed
+20% to Spell Damage
+20 Maximum Stamina
(25 to 30)% Gold Find
(25 to 30)% Magic Find
Requirements -60%
Socketed (4)
Belt:
Moonwrap
Moonwrap
Sash (4)
Defense: (16 - 18) to (20 - 21)
Required Level: 1
Required Strength: 25
Item Level: 1
5% Cast Speed
+3% to Spell Damage
+(18 to 29)% Enhanced Defense
Lightning Resist +(11 to 15)%
Cold Resist +(11 to 15)%
Socketed (1)
Defense: (119 - 129) to (131 - 141)
Required Level: 17
Required Strength: 50
Item Level: 20
15% Cast Speed
+9% to Spell Damage
+(41 to 52)% Enhanced Defense
Lightning Resist +(21 to 25)%
Cold Resist +(21 to 25)%
Socketed (2)
Defense: (331 - 353) to (370 - 395)
Required Level: 35
Required Strength: 125
Item Level: 41
25% Cast Speed
+15% to Spell Damage
+(64 to 75)% Enhanced Defense
Lightning Resist +(31 to 35)%
Cold Resist +(31 to 35)%
Socketed (2)
Defense: (493 - 524) to (542 - 576)
Required Level: 43
Required Strength: 250
Item Level: 72
30% Cast Speed
+20% to Spell Damage
+(75 to 86)% Enhanced Defense
Lightning Resist +(36 to 40)%
Cold Resist +(36 to 40)%
Socketed (2)
Gloves:
Vilehand
Vilehand
Leather Gloves (4)
Defense: 6 to 8
Required Level: 1
Required Strength: 25
Item Level: 1
+(3 to 5)% Bonus to Poison Skill Duration
+(6 to 10)% to Poison Spell Damage
Poison Length Reduced by (31 to 35)%
Socketed (1)
Defense: 70 to 75
Required Level: 17
Required Strength: 50
Item Level: 20
+(0 to 1) to All Skills
+(6 to 8)% Bonus to Poison Skill Duration
+(11 to 15)% to Poison Spell Damage
Poison Length Reduced by (36 to 40)%
Socketed (2)
Defense: 176 to 184
Required Level: 34
Required Strength: 175
Item Level: 40
+1 to All Skills
+(8 to 10)% Bonus to Poison Skill Duration
+(16 to 20)% to Poison Spell Damage
Poison Length Reduced by (41 to 45)%
Socketed (3)
Defense: 243 to 258
Required Level: 43
Required Strength: 350
Item Level: 72
+1 to All Skills
+(11 to 13)% Bonus to Poison Skill Duration
+(21 to 25)% to Poison Spell Damage
Poison Length Reduced by (46 to 50)%
Socketed (4)
Helm:
Farnham's Flowerpot

Farnham's Flowerpot
Full Helm (4)
Defense: (126 - 141) to (207 - 229)
Required Level: 6
Required Strength: 25
Item Level: 9
-(1 to 3)% to Enemy Elemental Resistances
+(41 to 60)% Enhanced Defense
+(21 to 50) Defense
(3 to 5)% to Vitality
Fire Absorb 1%
Lightning Absorb 1%
Cold Absorb 1%
Requirements -15%
Random Movement Speed Bonus
Socketed (1)
Defense: (477 - 519) to (711 - 768)
Required Level: 23
Required Strength: 48
Item Level: 27
-(4 to 6)% to Enemy Elemental Resistances
+(71 to 90)% Enhanced Defense
+(101 to 200) Defense
(6 to 10)% to Vitality
Fire Absorb 1%
Lightning Absorb 1%
Cold Absorb 1%
Requirements -20%
Random Movement Speed Bonus
Socketed (3)
Defense: (1225 - 1313) to (1630 - 1746)
Required Level: 41
Required Strength: 147
Item Level: 48
-(7 to 9)% to Enemy Elemental Resistances
+(101 to 120)% Enhanced Defense
+(301 to 400) Defense
(11 to 15)% to Vitality
Fire Absorb 2%
Lightning Absorb 2%
Cold Absorb 2%
Requirements -30%
Random Movement Speed Bonus
Socketed (4)
Defense: (1958 - 2078) to (2526 - 2685)
Required Level: 49
Required Strength: 252
Item Level: 82
-(10 to 12)% to Enemy Elemental Resistances
+(131 to 150)% Enhanced Defense
+(501 to 600) Defense
(20 to 25)% to Vitality
Fire Absorb 2%
Lightning Absorb 2%
Cold Absorb 2%
Requirements -40%
Random Movement Speed Bonus
Socketed (4)
or
Glowskull

Glowskull
Crown (4)
Defense: (164 - 187) to (248 - 281)
Required Level: 10
Required Strength: 26 to 29
Item Level: 17
+(6 to 8)% Bonus to Poison Skill Duration
+(4 to 6)% to Poison Spell Damage
-3% to Enemy Poison Resistance
+(41 to 60)% Enhanced Defense
Poison Resist +(16 to 25)%
(11 to 20)% Bonus to Defense
Requirements -(11 to 20)%
Socketed (1)
Defense: (561 - 620) to (785 - 868)
Required Level: 28
Required Strength: 50 to 56
Item Level: 32
+(11 to 13)% Bonus to Poison Skill Duration
+(10 to 12)% to Poison Spell Damage
-6% to Enemy Poison Resistance
+(81 to 100)% Enhanced Defense
Poison Resist +(36 to 45)%
(21 to 30)% Bonus to Defense
Requirements -(16 to 25)%
Socketed (3)
Defense: (1272 - 1392) to (1754 - 1920)
Required Level: 46
Required Strength: 165 to 186
Item Level: 53
+(16 to 18)% Bonus to Poison Skill Duration
+(16 to 18)% to Poison Spell Damage
-9% to Enemy Poison Resistance
+(101 to 120)% Enhanced Defense
Poison Resist +(56 to 65)%
(31 to 40)% Bonus to Defense
Requirements -(21 to 30)%
Socketed (4)
Defense: (1911 - 2076) to (2614 - 2839)
Required Level: 54
Required Strength: 306 to 349
Item Level: 90
+(18 to 20)% Bonus to Poison Skill Duration
+(18 to 20)% to Poison Spell Damage
-12% to Enemy Poison Resistance
+(121 to 140)% Enhanced Defense
Poison Resist +(66 to 75)%
(41 to 50)% Bonus to Defense
Requirements -(26 to 35)%
Socketed (4)
Rings/Amu: rare +psd/pierce/skill
There's probably other options in runewords and you can certainly replace some spots with reasonable rares you find or honorifics.
You can make progress without having all those things, its a strong build.
I definitely looked more on the offensive side while compiling this (i.e. pierce, psd, +skills)