The most likely archetype to be viable from the newest box “Rampage of the Forest” is the Sylvan archetype. This plant based deck revolves around excavating cards from the top of your deck, and if Sylvan monsters get excavated they have effects that can be activated.
Most Sylvan deck lists you’ll see will only run a few spells/traps because your strategy will be to clear your opponent’s backrow and monsters with the help of your Sylvan monsters and to consistently excavate Sylvan monsters you need to run a lot of them.
Low-Leveled Sylvans excavate only once with their effects, Komushroom when he is flipped face-up and Marshalleaf when he is summoned making them less useful to keep on the field. But being easier to put on the field makes them good opening plays. The best opening play would be to set Komushroom and wait for your opponent to attack into it and excavate 5 cards from your deck. Additionally, these two monsters have the best effects when they are excavated. Komushroom destroys a spell/trap card on the field while Marshalleaf destroys a monster, and chaining them together with other Sylvan effects makes them impossible to negate.
After using their excavate effects they have little use on the field. Komushroom can stay as a wall and Marshalleaf is a below average beater, but it would be best to tribute them into your high-leveled Sylvans. Hermitree is your biggest beater and allows you to draw cards while excavating your deck, although needing 2 tributes makes him the most difficult to summon of the bunch. Guardioak and Lotuswain allow you to excavate multiple cards from the top of your deck, with the number of cards Lotuswain is able to excavate depending on the number of cards your opponent controls. When excavated, these monsters have effects to help you manage the arrangement of your deck that you only excavate what you need and not unnecessarily excavate cards you might want to draw.
To summon these high-leveled monsters consistently, using the low-leveled Sylvans as tribute would not be enough. Send Naturia Pineapple to the graveyard so that he can be revived every turn to use as tribute. Amarylease is like a worse Rose Lover, you can banish him from the graveyard to summon a monster for 1 less tribute. (0 tributes if it originally required only 1 tribute.)
Since you want Naturia Pineapple and Amarylease in your graveyard, it would be bad if they got stuck in your hand. As a solution you can send them to the graveyard to special summon World Carrotweight Champion from your graveyard. Carrotweight can then be used as a beater or as tribute to summon Sylvan Hermitree in combination with Amarylease. You can also send the low-leveled Sylvans to the grave to revive Carrotweight after you are done using their excavation effects.
Negating monster effects with Ultimate Providence is really good as it also destroys the monsters. And with so many monsters in this deck you will almost always be able to use Ultimate Providence on your opponent's monster. Another great thing about this, is that you can use this discard to put Naturia Pineapple or Amarylease in your graveyard for later use. Monsters you can negate include Amazoness Princess to stop Amazoness decks from setting up, Spellbook Magician of Prophecy to stop Spellbooks from using Spellbook of the Master and Spellbook of Fate, and Masked HERO Anki to stop Masked Heroes from extending their attacks.
How to Use (Pre-Banlist)
When you start to duel you’ll want to Restart to look for cards like Sylvan Komushroomo, Sylvan Marshalleaf and Magical Merchant, so that you can start excavating cards as soon as possible.
The optimal way this deck works is you excavate cards with the effects of Magical Merchant, you get rid of your opponent’s cards with the effect of Komushroomo and Marshalleaf (when they are excavated), you maybe excavate a Rose Lover so you can special summon a high attack monster and draw into Raging Mad Plants with Magical Merchant’s effect, which should make you able to defeat your opponent very quickly.
Because the Sylvan cards have a lot of text, we’ll add a very short TL;DR (Too Long Didn’t Read) after we talk about each Sylvan card.
The best cards to have in your opening hand are probably Magical Merchant and Sylvan Komushroomo. Magical Merchant can excavate a large amount of cards at times, because the deck only runs two cards to stop the excavating (Raging Mad Plants). With Sylvan Komushroomo you’ll want to excavate 5 cards in most situations, and with Sylvan Marshalleaf you want to excavate 2 cards.
Sylvan Komushroomo and Sylvan Marshalleaf have the most powerful effects of all the Sylvan monsters available when they are excavated themselves because you can destroy a spell/trap and monster respectively.
The only two monsters in this deck that normally would require (a) tribute(s) in order to be summoned, but since this deck runs three copies of Rose Lover, you have a high chance of sending some of those Rose Lovers to the graveyard thanks to all the excavating you’ll be doing. That way you can special summon those high level monsters easily to apply huge amount of pressure on your opponent.
Sylvan Hermitree can excavate one card per turn, and if it was a plant you can draw one card. If he was excavated you look at the top three cards in your deck and place them in any order.
Sylvan Hermitree can excavate one to three cards each turn, and if he was excavated himself you can place one plant on the top of your deck.
Sometimes you’ll want to tribute summon Sylvan Guardioak so you can get rid of useless monsters on the field like Sylvan Komushroomo (after he is flipped face-up) .
Although these two monsters are the best Sylvan beatsticks, you don’t actually want to run three copies of each because most of your normal summons/sets will be used for Sylvan Komushroomo and Sylvan Marshalleaf. However they are both decent targets to special summon with Rose Lover as well in case you don’t have any of your high attack monsters in hand and you can go for game, or get rid of a lot of your opponent’s monsters (which is important in games against Gladiator Beasts for example).
An extremely powerful card in this deck which will allow you to finish of games very quickly. You’ll consistently draw into this card thanks to the effect of Magical Merchant and because you’ll be sending a lot of Plant monsters to the graveyard this card will easily boost your monsters with more than 1500 attack. (don’t forget it boosts all of your plant monsters on the field).
In the TCG/OCG you can decide in which order you want to activate effects from excavated Sylvans, however in Duel Links the order of activation will be decided in what order they were sent to the graveyard (first on send to the graveyard; first one to activate).
Magical Merchant is an insect monster, so when it is excavated with the effects of a Sylvan monster it will be placed on the bottom of your deck.
Sylvan effects only activate when they are “excavated” , so it doesn’t work with cards like “That Grass looks greener”.
Activate Raging Mad Plants in your damage step to play around cards like Enemy Controller, Windstorm of Etaqua, Curse of Anubis, …
The deck is listed as expensive because you need three copies of Sylvan Komushroomo in an optimal build, and since it’s an SR in a box with 80 packs this can be hard to obtain.
I think Sylvans are still viable. I use this deck with a variation of spell/trap cards depending on the meta. Between rose lover and marshalleaf i would go rose lover. I've been in high/mid plat multiple seasons and can beat the top tier decks about half the time. Easy set-ups.
Haven’t really seen too many sylvans trying to make a come back in pvp since the nurfs. Occasionally, I’ll see a player or two trying to make it work but the most they can hope for is a beat down with their bigger monsters. I guess decks who rely on back row can still be annoyed with komushroom.
I have tried to make a Sylvan with Luna's skill mark of the hand. Not bad, but still not competitive enough. Sometimes you mill good, sometimes you don't mill anything. But if you mill good, you can get a board of Guardioak, Stardust Dragon and Carrot. 3 Magical merchants and 2 Spell cards build.