Things You'll Need
Instructions
Playing the Perma Sin
When first learning a Shadow Form Assassin, or "Perma Sin," you would be well-advised to spend some time learning the principles of the build. Shadow Form is the Elite skill which the entire build is focused around. It grants the Assassin temporary invulnerability to damage, but has a lengthy cool-down timer. Skills, such as the Elementalist's Glyph of Swiftness, allow you to reuse Shadow Form before its duration is over. Combined with a weapon modifier that extends enchantment durations, you can effectively be permanently invulnerable.
Your core Assassin skill-set must include Shadow Form and Glyph of Swiftness. Everyone else is up to you to pick, but recommended skills include Sliver Armor, Death Blossom and any degeneration attacks -- poison, bleeding, disease and hexes all ignore Shadow Form's damage reduction. Once you have chosen your skill-set, get a good feel for how the energy economy flows. Invest four stat points into Air Magic, 16 into Shadow, and spend a few in Critical Strikes to give you energy boosts off your auto-attacks.
It is important that your equipment be up to the job. At a minimum, you will require a weapon with +20% Enchantment duration, but armor with energy increase modifications or death-element resistance will also help. On occasion, it is likely that you will slip and take a few hits before you restore Shadow Form, so being equipped to survive those mistakes is essential to a full clear.
Once you have entered the Underworld, refrain from chain-pulling enemies. Fight them one at a time, always being careful to maintain Shadow Form and Glyph of Swiftness. Unholy Necromancers and Light Spirits all have Enchantment removal abilities, so when you encounter them, use "cover enchantments" to prevent your lifeline, Shadow Form, from being cut. Enchantment removal prioritizes the most recent enchantments first, so when you see them begin to cast their disenchantment spells, throw up an instant-cast enchantment on yourself to block them. Repeat this process, always being sure to be as slow and careful as you can be, until you have cleared out the Underworld.