Setup

There are 3 major variants of this build:

Assassin/Elementalist
Glyph of Swiftness
Deadly Paradox
Shadow Form

High Shadow Arts, 16 is recommended. A 20% of Enchanting weapon is needed (15% is ok too but it is a little harder to maintain). Runes of Attunement and Radiant Insignias are needed, as 30 energy is needed before casting.

Use Glyph of Swiftness and Deadly Paradox before casting Shadow Form.

This build is used in the UW to farm the Chaos Planes.

EotN Glyph of Swiftness 10 1 5 Glyph. For 15 seconds, your next 1..3..3 Spells recharge 25% faster, and projectiles from those spells move 200% faster. (Attrib: Air Magic) Nightfall Deadly Paradox 10 15 Stance. All of your attack Skills are disabled for 10 seconds. For 5..13..16 seconds, your Assassin Skills activate and recharge 33% faster. (Attrib: Deadly Arts) Factions Shadow Form (PvP) 60 1 10 Elite Enchantment Spell. For 13 seconds, all hostile Spells that target you fail and all attacks against you miss. When Shadow Form ends, lose all but 41 Health. (Attrib: 12 Shadow Arts) Core Glyph of Lesser Energy 30 1 5 Glyph. For the next 15 seconds, your next 2 Spells cost 10 less Energy to cast. (Attrib: 0 Energy Storage) Prophecies Lava Font 4 2 10 Spell. For 5 seconds, foes adjacent to the location where this Spell was cast are struck for 41 fire damage. (Attrib: 12 Fire Magic) Factions Bed of Coals 30 1 10 Spell. Create a Bed of Coals at your location. For 10 seconds, foes standing still near this location are struck for 24 fire damage each second. Any foe knocked down on the Bed of Coals is set on fire for 6 seconds. (Attrib: 12 Fire Magic) Prophecies Whirlwind 8 ¾ 5 Spell. All adjacent foes take 15..51..63 cold damage. Attacking foes struck by Whirlwind are knocked down. (Attrib: Air Magic) Core Fire Attunement 45 2 10 Enchantment Spell. For 55 seconds, you are attuned to Fire. You gain 1 Energy plus 30% of the base Energy cost of the Skill each time you use Fire Magic. (Attrib: 12 Fire Magic)

Perma Form UW

Assassin/Mesmer
Arcane Echo
Deadly Paradox
Shadow Form

High Shadow Arts, 16 is recommended. A 20% of Enchanting weapon is also recommended. Runes of Attunement and Radiant Insignias are needed, as 40 energy is needed before casting.

Use Deadly Paradox and then Arcane Echo before casting Shadow Form. Before the echoed copy of Shadow Form expires, cast it. (This method requires more energy than assassins gain through energy regeneration. Consider using energy management skills to maintain Shadow Form indefinitely.)

Nightfall Deadly Paradox 10 15 Stance. All of your attack Skills are disabled for 10 seconds. For 7 seconds, your Assassin Skills activate and recharge 33% faster. (Attrib: 3 Deadly Arts) Core Arcane Echo 20 2 15 Enchantment Spell. If you cast a Spell in the next 20 seconds, Arcane Echo is replaced with that Spell for 20 seconds. Arcane Echo ends prematurely if you use a non-Spell skill. Factions Shadow Form (PvE) 60 1 10 Elite Enchantment Spell. For 25 seconds, all hostile Spells that target you fail and all attacks against you miss, but you deal 50% less damage. When Shadow Form ends, lose all but 41 Health. (Attrib: 12 Shadow Arts) Prophecies Spirit of Failure 20 3 15 Hex Spell. For 30 seconds, target foe has a 25% chance to miss with attacks. You gain 3 Energy whenever that foe fails to hit in combat. (Attrib: 12 Inspiration Magic) Prophecies Channeling 15 1 5 Enchantment Spell. For 46 seconds, whenever you cast a Spell, you gain 1 Energy for each foe in the area. (Attrib: 12 Inspiration Magic) Factions PvE only Ether Nightmare (Kurzick) 15 3 10 Hex Spell. Target foe loses 4..8 Energy. For each point of Energy lost in this way, that foe and all foes in the area suffer -1 Health degeneration for 10 seconds. (Attrib: Kurzick rank) EotN PvE only Radiation Field 12 2 15 Ward Spell. For 5 seconds, foes in the area have -2..6 Health degeneration. When the portal ends, foes in the area are Diseased for 8..20 seconds. (Attrib: Asura rank)

Perma Form Cryer 1

Nightfall Deadly Paradox 10 15 Stance. All of your attack Skills are disabled for 10 seconds. For 7 seconds, your Assassin Skills activate and recharge 33% faster. (Attrib: 3 Deadly Arts) Core Arcane Echo 20 2 15 Enchantment Spell. If you cast a Spell in the next 20 seconds, Arcane Echo is replaced with that Spell for 20 seconds. Arcane Echo ends prematurely if you use a non-Spell skill. Factions Shadow Form (PvE) 60 1 10 Elite Enchantment Spell. For 25 seconds, all hostile Spells that target you fail and all attacks against you miss, but you deal 50% less damage. When Shadow Form ends, lose all but 41 Health. (Attrib: 12 Shadow Arts) Prophecies Spirit of Failure 20 3 15 Hex Spell. For 30 seconds, target foe has a 25% chance to miss with attacks. You gain 3 Energy whenever that foe fails to hit in combat. (Attrib: 12 Inspiration Magic) Prophecies Channeling 15 1 5 Enchantment Spell. For 46 seconds, whenever you cast a Spell, you gain 1 Energy for each foe in the area. (Attrib: 12 Inspiration Magic) Factions PvE only Ether Nightmare (Luxon) 15 3 10 Hex Spell. Target foe loses 4..8 Energy. For each point of Energy lost in this way, that foe and all foes in the area suffer -1 Health degeneration for 10 seconds. (Attrib: Luxon rank) EotN PvE only Radiation Field 12 2 15 Ward Spell. For 5 seconds, foes in the area have -2..6 Health degeneration. When the portal ends, foes in the area are Diseased for 8..20 seconds. (Attrib: Asura rank)

Perma Form Cryer 2

The sixth skills are optional.

Farming Spots

-The FoW beach and spider cave.
-The Underworld: clear the chamber of everything, then clear everything on the way to the mountains (where the obsidian behemoths are), kill everything on the way to the smite crawlers, and then do the Unwanted Guests quest.
-Ice Imps in Mineral Springs for the occasional Icy Dragon Sword drop.
-Tombs of the Primeval Kings
-Anywhere in Prophecies, Factions, and Eye of the North that doesn't have hex removal,signets, touch skills, or weird enchant removal.
-Feather farming outside of Lions Arch. (About 60-90 feathers a run and the runs take around 5-10 mins, depending on if they stay balled up)
-ToPK (First room and all of the second room except wurms - run to the platform in the middle).

Assassin + Consumables
Deadly Paradox
Shadow Form

High Shadow Arts, 16 is recommended. A 20% of Enchanting weapon is also recommended. Essence of Celerity essentially replaces Glyph of Swiftness, opening up the secondary.

This Build is mainly used in FoWsc's. It uses Glyph of Lesser Energy to help maintain your skills since the consumable is letting you cast faster.

Nightfall Deadly Paradox 10 15 Stance. All of your attack Skills are disabled for 10 seconds. For 5..13..16 seconds, your Assassin Skills activate and recharge 33% faster. (Attrib: Deadly Arts) Factions Shadow Form (PvE) 60 1 10 Elite Enchantment Spell. For 25 seconds, all hostile Spells that target you fail and all attacks against you miss, but you deal 50% less damage. When Shadow Form ends, lose all but 41 Health. (Attrib: 12 Shadow Arts) Core Glyph of Lesser Energy 30 1 5 Glyph. For the next 15 seconds, your next 2 Spells cost 10 less Energy to cast. (Attrib: 0 Energy Storage) EotN PvE only Ebon Battle Standard of Honor 20 1 10 Ward Spell. You plant an Ebon Battle Standard of Honor at your current location. For 10..20 seconds, non-Spirit allies in this area strike for +5..15 damage and an additional +5..10 vs. Charr. (Attrib: Ebon Vanguard rank) Factions Sliver Armor 30 1 10 Enchantment Spell. For 10 seconds, you have 45% chance to block attacks and whenever you are the target of a hostile Spell or attack one nearby foe is struck for 29 earth damage. (Attrib: 12 Earth Magic) Factions Death's Charge 30 ¼ 5 Spell. Shadow Step to target foe. If that foe has more Health than you, you are healed for 173. (Attrib: 12 Shadow Arts) Nightfall Feigned Neutrality 25 ¼ 5 Enchantment Spell. For 9 seconds, you have +7 Health regeneration and +80 armor. This Enchantment ends if you successfully hit with an attack or use a Skill. (Attrib: 12 Shadow Arts)

FoW T1

Variants

Daggers - Frequently utilizes Death Blossom because of the AoE damage and fast recharge. Also, skills that require an enchantment can be easily utilized. However, this variant is hurt by the recharge to attack skills caused by Deadly Paradox.

Degeneration - Degeneration isn't hurt by Shadow Form's damage reduction, giving this variant some extra punch. Can utilize burning, AoE hexes, or wards.

Tanking - Perma SF sins can make effective tanks, as very little damages them. In some cases there can be multiple perma SF sins, so that one can hold aggro for the rest of the group to kill, while the other starts aggroing the next mob.

Earth Magic - Earth magic is mainly used for Sliver Armor. This is a good skill for boss farming, and can be quite successful in mob farming. It's advised to get air magic to 4, so Glyph of swiftness can reduce Sliver as well as SF.

Nuking - This is just a fire elementalist, with Meteor Shower, Fire Storm and other high damaging AoE skills.


Information from wiki.guildwars.com