I was looking into this recently and would like to know if they are competitive and if so what is needed to make it so?

Not competitive, and really expensive...
But if you want a quick build: it should look like:
Zil, the living shadow, abomination,saphyra the zil. (saphyra is the only one you MUST have. The other two can be replaced by other cheaper marauder, such as the shadow,the spooker, telendaror even Bloodsword)
3*artrezil s blade (if they are too expensive, just use telendar's blade and shadowblade...)
2*telendar s black blade
1*shadowblade(get 3 on nebsen weeks...)

3*master assassin
1*artrezil s heritage
1*time to die
2* hidden blades
2*dexterity game
Juggle
ziloween
1-2* stirring up hatredor toffee apple (put that on the freaking OPlegendary the'yll die much faster )
1*the secret of the crow
1*difference of opinion.

add paranoïa when there is no nebsen to screw courtiDD gameplay... (and discard those freaking OP Circles...)

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--EXYLEME--
"-oh mon dieu! ils ont tués Kenny!
-espèce d'enfoirés!"

Why is it not competative? It seems pretty strong to me.

The damage prevention of lot of decks limit the efficiency of this deck.
Against big defences with lot of damage prevention you can't do much.

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Collectionneur de cartes

Too many damage reduction. (nebsen and when he is banned, courti DD)
Pirate sniper do better for cheaper.

This is my favourite deck. I would really love seing it in Elo, but it's not good enough...

If you really want to play a zil aggro deck. I think it would be a better Idea to go for the guem deck.
viewtopic.php?f=122&t=138
(Hungry void and a new start are not mandatory... )

_________________
--EXYLEME--
"-oh mon dieu! ils ont tués Kenny!
-espèce d'enfoirés!"

I find this deck really amusing, especially since Dancing-Blade was released. With her order bonus, I was able to 1HKO Nebsen with the right cards

Artrezil's Daggers are great, but I would just include 2 of them because they're just OK against other Zils. Shadow Blades x3 because not only can they chain marauder cards, they basically destroy priest decks, and even immortals like Zehanie.
Zilloween and Civil War are essential cards too

Really fun with Juggle :3

Here is my new version of the deck:(25 cards)

Dancing blade - saphyra the zil - abomination(I sold my ZILd to make a crow deck, but he is still better than abo... )

objects:
3*artrezil blade (just the best dagger, be careful when facing zil decks... especially discard)
2*shadowblade (Really good for the chain, and the tooblox effect is nice against heal decks...)
2*fighting dagger (try to place it on saphyra, you can easily get a character with 15 attack before he plays his cards thanks to dancing blade and the dagger...)
2*mask of the murderer (can make awesome combo, but completely screws the drawing. So be careful to play it only if you already have things to play next turn in your hand. Or if it is going to be the last turn...)

actions:
1*time to die (I really hesitate to take it out since I don't use it that much. And there are only three cards I can chain it with in a 25 cards deck...)
3*master assassin (Damage dealer...)
3*hidden blades (Can lead to the best combo of the deck...)
2*it is time (really effective with the order of saphyra and dancing blade. It gives you a nice chaining card that can not be countered by dissidence...)
1*ziloween (try to play it with dancing blade. If she has not her order bonus, play it is time+ziloween, you won't even fear dissidence and you'l deal massive damage...)

Toolbox:
Difference of opinion
The secret of the crow
Sentence (counters immortals, nebsen,flamara and pirate golem. in combination with shadowblade, it is really powerful...
Dissidence (no need to explain...)
Slippery weapon (I would like to add one more, but I fear I'll have too much cards then... :s)
Anathemize (counter admiral, undead, Entropy and stone linker AOE...)

_________________
--EXYLEME--
"-oh mon dieu! ils ont tués Kenny!
-espèce d'enfoirés!"

I like dancing blade.. I put together a deck with her saphyra and zil (telendar works too) to get the seeds and it was fun putting artrezil blade + hidden blade on her.. and if you get another artrezil from hidden blades, lots of damage dealt..

Although I feel it won't go top in amnezy, but real fun..

is this deck playable in elo ?

Playable: yes, good: not really...

_________________
--EXYLEME--
"-oh mon dieu! ils ont tués Kenny!
-espèce d'enfoirés!"