Just like how Lightsworns in the TCG generate advantage by excavating cards, Sylvans operate the same way. Because of this, Sylvans manage to generate incredible pluses off their cards while harmonizing with other cards in the deck.

Firstly, credits to /u/ShatteredSkys as he introduced this Deck on Reddit. /u/ShatteredSkys also reached King Of Games with the deck which proves that the deck packs a punch.

Sylvans - KOG DECK
Monsters	Sylvan Komushroomo x3 Sylvan Flowerknight x2 Sylvan Hermitree x3 Rose Lover x3 Sylvan Marshalleaf x3
Spells	Tribute to the Doomed x2 Cosmic Cyclone x2
Traps	Floodgate Trap Hole x2

Introduction

To begin, make sure you have the skill 'Restart' since it can help dig for your 'Mushroomo' and stop bricky hands. As said in the excerpt, Sylvans aims to mill cards from the deck to the grave and benefit from those resources. With a bit of a luck element involved, you'll realize that some of the plays can be heavily dependent on the mills.

Once you mill cards like 'Rose Lover' to the grave, we can start summoning boss monsters like 'Sylvan Hermitree'. What's really fun about this deck is getting incredibly good mills that can snowball the game in your favor. Sylvans is a deck that overwhelms your opponent. Your opponent will waste many resources trying to out your board, but the more you mill the harder your deck is to stop.

Sylvans is also open to customization. Adding in different engines like the Dark World or Lightsworn can really make the deck feel unique. Just by using other methods to excavate, you can adapt this deck according to the meta. Without a further ado, let's begin the breakdown of this deck!

Card Explanations

Monsters

Sylvan Komushroomo

What an amazing card. Honestly. Sylvan Komushroomo mills, saves the spells/traps, and even operates to destroy back-row. In Yu-Gi-Oh! Duel Link's format, being able to mill five cards can be game changing, especially when milling the right five cards could give you the win straight away. That being said, Sylvan Komushroomo is a must-have in this deck and can't really be replaced due to the sheer power it brings to the archetype.

Sylvan Hermitree

If you were in an anime, this would be your ace card. Since it can set up your plays by being excavated, you won't be disappointed when you mill this to the grave. If you draw into it or start with this, you can also special summon it with the effect of 'Rose Lover'. Hence, you have easy access to a 2700 attack monster which also helps you generate advantage. Like /u/ShatteredSkys has said, it is a card that allows you to play a slower game. By utilizing its effect to excavate and draw, you'll start to see more approaches to the duel at hand.

Rose Lover

An absolute staple. Sylvans is a deck that operates with cards whose effects generate advantage in the grave. 'Rose Lover' is one of the main cards that you're hoping to mill since its an easy summon to whatever monster you have in your hand, preferably Sylvan Hermitree. That being said, you'd definitely need to run three of these and I can't see a deck running fewer.

Sylvan Flowerknight

Sylvan Flowerknight is a card with decent attack. You'd want to excavate it to the grave or summon it for its effect. Since it can guarantee a Sylvan card through its mill, it helps set up your engine for future plays. If you're playing in a tournament, you might want to side this out. While it gets you the cards you need, it might be underwhelming if you draw into more of these.

Sylvan Marshalleaf

Sylvan Marshalleaf is a card which helps with board control. By running three of these, you can truly dismantle your opponent's board no problem. First thing's first, his excavation effect annihilates anything that you see fit to be destroyed. By doing so, you open up the board and make your opponent vulnerable. Not only that, but Sylvan Marshalleaf can start your engine since it is a normal summonable monster. Milling two cards is great, especially with how small decks are in Duel Links. All in all, make sure you run three of these since it'll probably net you some easy wins.

Spells

Dark Core

Instead of 'Tribute to the Doomed', Dark Core is a card which helps prevent graveyard monsters from getting advantages. Basically, Sylvan Marshalleaf already pops face-down monsters, but destruction isn't always the best option. It helps when you need to banish instead of destroy and another form of removal is always great in a deck.

Cosmic Cyclone

I like Cosmic Cyclone opposed to a card like 'Hey! Trunade' since its effect is permanent. Rarely do cards in Duel Links recycle back spells/traps and by removing them from play, you can stop your opponent from gaining advantage off it. If you use Hey! Trunade, know that you better finish your opponent off since they'll just set those cards right back. If you don't have either of these cards, you can also try the infamous Anti-Magic Arrows. Like I said before, the deck is incredibly customizable and you can edit it to how you see fit.

Traps

Floodgate Trap Hole

Yeah, this card is just too good to not play. I mean, you can replace this with Wall Of Disruption but how depressing would it be to instantly shut down your opponents boss monsters after they summon them. You can replace this card with any back-row oriented trap, but generally a Floodgate Trap Hole works wonders and is incredibly versatile to whatever new deck that come outs.

Main Objective

The main objective of the deck is to mill cards until you generate enough advantage to take out your opponent. Summoning cards like 'Sylvan Marshalleaf' and 'Sylvan Flowerknight' can help start your engine. Even splashable cards like 'Lyla, Lightsworn Sorceress' can help cycle through your cards. You just need to excavate your cards to the grave.

For these reasons, you might find that Sylvans can be quite luck-oriented since the advantages gained will be random. You pray for Sylvan Marshalleaf to be milled when your opponents have a monster. But since Yu-Gi-Oh! Duel Links decks only contain twenty cards, you'll just need to use Sylvan Komushroomo once or twice to get the resources needed.

Grinding long duels for Sylvan should be no problem. In my personal experience, I find that once resources are in the grave victory becomes imminent. Even when you have trouble outing a card on the field, you can use cards like Dark Core to aid you. It largely comes down to how you use your tech cards to determine victory.

Final Thoughts

Since Sylvans is extremely similar to how Lightsworns operate in the TCG, you might find your opponents more prone to saltiness. The main gripe about the deck is how luck-oriented can be. However, every card milled is something to be accounted for. For a deck capable of reaching King Of Games, it's not only fun but also rewarding.

Summoning monsters correctly at the right times and disrupting the correct things will guarantee victory. The deck doesn't make the duelist, it's the duelist making the plays. For that reason, I want to end this article by begging you to give this deck a try. It is truly fun hoping for lucky mills and watching your opponent tremble in fear of a humongous tree. Thanks for reading!