Perma Shadow Form

These builds are based around permanently maintaining Shadow Form, protecting the user from spells and dramatically reducing damage from attacks. There are a number of variations, since the core of the build requires only 2 skills. They are typically used for farming and speed clears.

Assassin/any + Consumables
Consumables such as Essence of Celerity can help you to mantain Shadow Form constantly, freeing one skill slot in your build and saving your energy.

Assassin/any or any/Assassin
Using Deadly Paradox allows any primary or secondary Assassin to maintain Shadow Form, though it does cost three times as much energy as Glyph of Swiftness. High Shadow Arts (16) and a +20% enchanting weapon are also recommended.

Assassin/Elementalist
High Shadow Arts, 16 is recommended. A 20% enchanting weapon is needed (15% is ok too but it is a little harder to maintain).

Use Glyph of Swiftness before casting Shadow Form.

Assassin/Ranger
If you don't need specific secondary profession, this setup allows to spam attack skills with reduced recharges that Deadly Paradox would disable otherwise.

Use Dwarven Stability and Serpent's Quickness before Shadow Form. If you have Dwarven rank high enough it is possible to mantain SF even with 0 Wilderness Survival this way.

Quickening Zephyr
Assassin/any

Ranger/any or Any/Ranger

The second player (or hero) constantly mantains QZ, while the first player is tanking/farming in the spirit's range. Under effect of Quickening Zephyr it is possible to maintain Shadow Form even with 8 Shadow Arts. But keep in mind that all your skills cost 30% more energy.

Synergy
Shadow Form synergizes well with skills that block attacks and increase armor. For example, combined with Shroud of Distress, Mental Block and Great Dwarf Armor it provides 87.5% chance to block, decreased damage and health regeneration.

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 Shadow Form's damage limit, which makes daggers useless against any foes having self-healing.

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 Armor as well as SF.

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

Duration analysis
Note: Casting reduction from various sources was not calculated in this table.

Assassin/any + Essence of Celerity
+20% Enchantment Mod is required. Casting on recharge costs 0.2 energy/second. 1Cost in Energy/Second. 4 Energy regeneration is 1.33 per second.
 * Shadow form recharges every 24 seconds and costs 5 energy.

Assassin/Elementalist
Using Glyph of Swiftness and Shadow Form + 20% Enchant Mod Casting on recharge costs 0.44 energy/second.
 * Shadow form recharges every 22.5 seconds and costs 10 energy.

Using Quickening Zephyr without Enchantment Mod
Casting on recharge costs 0.46 energy/second.
 * Shadow form recharges every 15 seconds and costs 7 energy.

Using Quickening Zephyr with Enchantment Mod
Casting on recharge costs 0.46 energy/second.
 * Shadow form recharges every 15 seconds and costs 7 energy.