
It is based on the dervish' avatar line of skills idea which gives players a different 'form'. It is because of this that i thought that it could go well with Shadow 'Form'.
One of the main problems with sf is that it provides practically complete invulnerability to most sources of damage whilst at the same allowing the user to inflict damage for it's duration. This coupled with the al's inability to detect SF and continually try (and fail) at attacking the user (which could trigger other skills such as sliver armor) makes it far too broken. I know that anet are going to address it, which is why i feel that this topic could be stupid, but i've been thinking of this idea for a while and i just wanted to see what everyone else thought. I also liked the idea of assassins being stealthy and sneaking around undetected. lol this may sound broken too but i tried to balance it so here it is anyways-
Shadow form-
Energy cost-10 / casting time-2secs / Recharge-30secs
"Form. This skill can only be used while not being the target of an ally or enemy. You lose all enchantments and cannot be targeted by spells from allies. For 5...20...45 seconds, you move 90...50...35% slower and cannot be detected by any nearby enemies. This changes to 75...35...20% when an enemy enters your nearby range. This skill ends immediately when you attack or cast a spell that targets an ally or enemy. When an enemy enters your adjacent range this skill ends. When this skill ends, for the next 2...6...10 seconds, you deal an additional point of damage for each second this skill was active with your next attack skill, spell or signet. This skill is disabled for 120 seconds. (50% failure chance unless critical strikes 3 or more) "
In case that was too complicated or harsh here's a revision of it-
Shadow form-
Energy cost-10 / casting time-2secs / Recharge-30secs
"Form. This skill can only be used while not being the target of an ally or enemy. You lose all enchantments and cannot be targeted by spells from allies. For 5...20...45 seconds, you move 90...45...30% slower and cannot be detected by any nearby enemies. This skill ends immediately when you attack or cast a spell that targets an ally or enemy. When an enemy enters your adjacent range this skill ends. When this skill ends, for the next 2...6...10 seconds, you deal an additional point of damage for each second this skill was active with your next attack skill, spell or signet. This skill is disabled for 60 seconds. (50% failure chance unless critical strikes 3 or more) "
For the form, i was thinking of a ghostly assassin as i wasn't sure if they could do a shadowy sin but a ghostly one has been done. So i was thinking of something along the lines of this but , maybe more a darker hue-

Some of you may have realized when you looked at the skill that it didn't say 'Elite Form'. This was intentional. I personally don't think this will be too abuse-able and as such i thought a demotion to just a 'normal form' would be fine, as all this skill does is make your aggro bubble smaller with a little bit of damage at the end. This wouldn't be the first time a skill has been demoted...second(lol)
Another thing you may have noticed is that it says only enchantments by allies which means you can cast your own spells on yourself including enchantments such as sliver armor although no enemy will target you...
If they do, you will find that you won't be invulnerable anymore...
This was mainly done so that you can leave a battle and heal yourself if you have a self heal.
All in all i think this could be a very plausible skill idea that could be implemented and could change the skill from being a farming skill to a utility skill for sins. This is emphasized more in that it only requires a tiny investment in critical strikes to work efficiently and i tend to find that if i spec highly in two other attributes i still have enough to put at least 3 in the last attribute. It would also still allow sins to explore with ease but promotes a bit maybe slightly more skill? as you have to try and evade enemies rather than run straight through them. It also (i would say anyways), promote skill in that it would cause sins to think before causing the skill to end as the longer they leave it the stronger the extra damage and there is only a smallish window with which to utilize the extra damage depending on how much you invest in the attribute. I got the damage idea with the stereotypical thinking that a sin should be able to quickly silence any enemies that discovers them. On that note, because i feel it may be imbalanced if other classes could use it (not sure why yet...but trying to think of it) so i added the 50% failure chance clause. I know this will mean it's somewhat linked to critical strikes and it's not linked to the attribute well in terms of theme but it would mean only sins could use it well and could give them more options with utilities, and could reinvigorate the common perception by many that assassins are sneaky, agile and stealthy. The gw manuscript even states/implies this-
"The Assassin walks the shadows, a deadly viper ready to strike at the heart when the enemy least expects it, nowhere and everywhere all at once."
I can already tell most of you will feel that this is similar to stealth in WoW and lol yes it is...very lol, but i thought it was an idea that could be implemented and a good one at that, though this is purely an opinion so i understand if some of you may not think this is a good idea. Yes this will go against the innovative-ness of gw trying to be different from other mmo's (if gw is still considered an mmo anyways) but it's not like it's got much more life in it (again...if any).
One last thing to note is that this skill was made/changed with pve in mind as that's where it is overpowered most. However, linking back to my wow comment this skill could be adjusted slightly for use in pvp whilst retaining the core idea of stealth as it has worked well in wow. Again however, i understand that the meta is very, very...VERY different so this could be a debatable point.
I hope this will be well received with positive comments but if otherwise i wouldn't mind reading it still.
oh and hope i don't get flamed too much for this still and sorry for the big wall of text and thanks for reading it if you did and yeah i think that's it
