Laval is an archetype that focuses on setting up its Graveyard to enable several effects and swarm the field with powerful Synchro monsters. Since Synchro Summoning is not in the game yet, Laval is basically missing all of its boss monsters, but we can take advantage of the fact that it fills the Graveyard with various FIRE monsters to summon Pyrorex or simply use Searing Firewall to summon high level tribute monsters.
Mighty as Fire Can be used after your Life Points are at 3000 or below. Play the Field Spell "Molten Destruction." If there already is Field Spell on your side of the Field, return it to your hand. This skill can only be used once per Duel.
Pyrorex is the boss monster of this deck: if you have exactly 5 FIRE monsters in your Graveyard, you can Special Summon it from your hand; when he is Special Summoned you can destroy a monster on your opponent’s side of the field and inflict damage to both players equal to half of its original ATK; his ATK is enough to get over some of the most common threats, excluding a Silent Magician LV8. Normally it would be difficult to get exactly 5 FIRE monsters in your Graveyard, but with this deck it’s not a problem at all: you have multiple monsters that can send cards to Graveyard and a Quick Play Spell that can get rid of the ones in excess. The damage taken from this monster’s effect can be used to activate Bastion’s skill, MIghty as FIRE, which will further boost the monsters on the field, while also weakening the opponent before entering the Battle Phase: after for example destroying a Dyna, Hero Fur Hire, your opponent will likely be left with low ATK monsters that won’t be enough to protect his Life Points.
Laval Cannon, when Flip or Normal Summoned, can Special Summon a banished Laval monster, but, since Laval Lakeside Lady is not in the game yet, the easiest way to utilize his effect would be to banish a Laval monster from the deck with Gold Sarcophagus. You can use Searing Firewall to banish a Laval from your Graveyard and then Normal Summon Cannon to Special Summon the monster you banished.
Laval Miller, when destroyed by battle, allows you to send 2 Laval monsters from your deck to the Graveyard: it’s a great way to set up your Graveyard, but the restriction on how Miller needs to leave the field is definitely a hindrance. If Miller is destroyed by a Recon while face-down or banished by Amazoness Onslaught or Spellbook of Fate, he will be pretty much useless.
Blaster is the best way to get cards into the Graveyard: when Normal Summoned, you can send 1 to 5 cards from the top of your deck to the Graveyard and the he will gain 200 ATK for each Laval monster sent by this effect. Blaster’s effect is not really precise, but we can still banish a few of the FIRE monsters he sends, if they are more than 5, with Searing Firewall.
Burner has 2100 ATK, meaning that under Molten Destruction he can get over Red-Eyes, Dyna and Amazoness Queen; he is a level 5 monster, but you can Special Summon him from your hand, if you have at least 3 Laval monsters with different names in your Graveyard. You can use Miller’s effect to send Cannon and Blaster to the Graveyard to Special Summon Burner on your turn or just tribute a Token generated by Searing Firewall.
The deck doesn’t have any card that can get rid of back row, so adding Cosmic Cyclone will allow you to swarm the field and attack more freely with your monsters boosted by Molten Destruction. Cosmic Cyclone brings your Life Points down to 3000, exactly enough to activate your skill, and it can also get rid of Amazoness Onslaught, which would otherwise be a problem since you are trying to set up your Graveyard.
Since summoning Tokens is rather easy, Enemy Controller can be a great card to use offensively in this deck: you can tribute a Token to take control of one of your opponent’s monsters or just use it during your opponent’s turn for protection.
Searing Firewall allows you to banish Laval monsters from your Graveyard and then Special Summon the same number of Tokens on the field; it’s a Quick Play Spell so you can use it during your opponent’s Battle Phase to block some attacks while also getting rid of excess monsters in your Graveyard for Pyrorex. You can alternatively use the Tokens for Creature Seizure, which is not in this deck, but it’s still a valuable option.
Since the deck doesn’t run any Trap Cards, Treacherous is an obvious great addition: it destroys two monsters on the field as long as there are no Trap Cards in your Graveyard.
The deck is not bad, but you may struggle with consistency: relying mainly on one monster is not really the best choice and you might end up sending both copies to the Graveyard with a Blaster.
Laval struggles against Amazoness, Fur Hires and Spellbooks because it’s not nearly as fast. If more cards like Rekindling and Laval Judgement Lord are added to the game, then it will actually have a chance to be competitive even before the release of Synchro monsters.
The Gold Sarcophagus + Laval Cannon combo is very good, but there is no particular reason to run it: the monsters are very limited and most of them can be summoned easily anyway.
Lyla can get rid of your opponent’s back row and she also mills two cards during the End Phase: Laval usually functions well with any other archetype with a similar mechanic, so she can be a great addition.
Flame Emperor requires two tributes, he can be summoned easily with the Tokens generated by Searing Firewall and he can take advantage of the FIRE monsters in your Graveyard to destroy Spells and Traps.
Chalice can be used to boost your monsters, negate your opponent’s monsters’ effects, but it can also be used to avoid taking damage from Pyrorex: if you are low on Life Points, his effect can be deadly.