Let's start with Mystical Space Typhoon:
Select 1 Spell or Trap Card on the field. Destroy it.
A basic S/T removal Card. It targets a S/T Card on the Field. It cannot target itself, ever.
Next, we have Nightmare's Steelcage:
This card remains face-up on the field for 2 of your opponent's turns. No monsters can attack. Destroy this card during your opponent's 2nd End Phase after this card was activated.
Steelcage is a Normal Spell Card that is allowed to remain on the Field. It's not treated as a Continuous Spell Card or any of the other types of Spell Cards that remain on the Field by themselves. This ability cannot be negated, so even if Imperial Order is active, Steelcage would remain on the Field. After two of your opponent's turns, it's destroyed by Game Mechanics. It has a Continuous Effect that stops monsters from attacking. If you activate this Card's effect via Diamond Dude, it would try to apply its effect, but since it's not on the Field, monsters can attack as usual.
Then, we have Creature Swap:
Each player chooses 1 monster they control and switches control of those monsters with each other. Those monsters cannot change their battle positions for the rest of this turn.
Creature Swap forces players to switch control of one of their monsters as long as they remain on the Field. Once the monsters switch control, if another effect takes control of the swapped monster temporarily, control reverts to the controller that Creature Swap has set. For example, if you use Creature Swap and give away a Sheep Token to your opponent, then take control of it with Mind Control, at the end of the turn, Mind Control would return the Sheep Token to your opponent. This is because Creature Swap determines a new controller for the monster, but it's very different from Cards like Change of Heart or Brain Control.
Creature Swap's effect doesn't target, and so, the monsters are chosen at resolution. The position of the monsters can be changed manually before activating Creature Swap. Monsters that cannot switch control are not a valid choice for Creature Swap, but monsters that are unaffected by Spell Cards are. If all of the eligible monsters are unaffected by Creature Swap or there are no more monsters on one side of the Field at the time it resolves, then Swap resolves without effect.
Moving on, we have Book of Moon:
Select 1 face-up monster on the field and flip it into face-down Defense Position.
Book of Moon targets a face-up monster on the Field. A very basic effect to flip monsters face-down.
Then, we have Dark Room of Nightmare:
Each time your opponent takes damage from a card effect, except "Dark Room of Nightmare", inflict 300 damage to your opponent.
Dark Room of Nightmare has a Trigger-like effect. It start a chain after the chain in which your opponent took Effect Damage resolves. Being a Continuous Spell Card, Dark Room must remain face-up until that chain resolves and until its own effect starts resolving in order to inflict the damage.
Moving on, we have Foolish Burial:
Send 1 Monster Card from your Deck to the Graveyard.
Burial sends a monster from the Deck to the Graveyard as part of its effect. It doesn't target, and it resolves properly even if Macro Cosmos is active. It's important to emphasize how it doesn't target: You don't need to declare which monster you are sending to the Graveyard upon activating Foolish Burial.
And then, we have Magical Stone Excavation:
Discard 2 cards to select 1 Spell Card from your Graveyard. Add it to your hand.
Discarding two Cards is a cost, and this effect targets a Card in the Graveyard. If this Card's effect is activated via Diamond Dude, you don't need to discard, but the effect would still target a Card in the Graveyard.
The last Spell Card for now is Allure of Darkness:
Draw 2 cards, then remove from play 1 DARK monster from your hand. If you do not have any DARK monsters in your hand to remove, send all cards in your hand to the Graveyard.
Allure of Darkness has no cost. All of its actions are part of its effect. Removing a DARK monster from Play happens after you draw two Cards, that is to say, non-simultaneously. Not only this means that a player cannot respond with Cards like Drastic Drop off, but also, it means that you can activate Allure of Darkness without holding a DARK monster in your Hand or even the certainty of drawing into one of those monsters.
If Imperial Iron Wall is active, you cannot activate Allure of Darkness. However, if Iron Wall is chained to Allure, then you proceed as usual. First draw two Cards, then, if you have a DARK monster, simply reveal it to your opponent and keep it in your Hand. This revealing confirms that you are trying to perform the first part of Allure's effect (you DO have a DARK monster, you just can't Remove it from Play). If you don't have a DARK Monster, then of course your entire Hand is sent to the Graveyard.
As for the Trap Cards, let's start with Acid Trap Hole:
Select 1 face-down Defense Position monster and flip it face-up. If the monster's DEF is 2000 or less, destroy it. If the monster's DEF is more than 2000, flip the monster to face-down Defense Position.
Acid Trap Hole targets a face-down monster. It must remain face-down until Acid Trap Hole resolves. If the monster has a FLIP Effect or an effect that activates when it's flipped, it will start a new chain after Acid Trap Hole resolves. If a Continuous Effect of other Cards on the Field would increase the DEF of the targeted monster if it was face-up, then you must take it into account when Acid Trap Hole resolves. However, do not apply any Continuous Effects of the targeted monster, such as immunity to Trap Cards.
Then, we have Mirror Force:
Activate only when an opponent's monster declares an attack. Destroy all Attack Position monsters your opponent controls.
Mirror Force is activated upon Attack Declaration. It destroys all of your opponent's monsters that are in Attack Position when it resolves. Since a lot of people have the MRD Mirror Force, note that the text is heavily outdated and Mirror Force doesn't actually negate attacks. So if a monster like Koa'ki Meiru Valafar that can't destroyed by Trap Cards attacks, the attack would still go through.
Moving on, we have Skull Invitation:
Each time a card(s) is sent to the Graveyard, inflict 300 damage to its owner for each card sent.
Invitation has a Continuous Effect. You apply it right after the Cards are sent to the Graveyard. If you are in the middle of a chain, apply it when the corresponding chain link is done resolving.
Then, we have Coffin Seller:
Each time a Monster Card(s) is sent to your opponent's Graveyard, inflict 300 damage to your opponent.
Coffin Seller is similar to Skull Invitation, only that it counts Monster Cards sent to the opponent's Graveyard and that it has a Trigger-like Effect instead ofa Continuous one. But most importantly, Seller always inflicts 300 points of damage, regardless of how many Cards are sent by a single event. So for example, if you use Dark Hole and destroy 3 of your opponent's monsters, you only inflict 300 points of damage.
Other Trap Cards used by Marik also include Nightmare Wheel:
Select 1 monster your opponent controls. It cannot attack or change its battle position. When it is removed from the field, destroy this card. During each of your Standby Phases, your opponent takes 500 damage.
Nightmare Wheel targets a monster upon activation and after it resolves. It also has a Trigger-like effect that inflicts Effect Damage during your Standby Phase.
We also have Metal Reflect Slime:
After activation, Special Summon this card in Defense Position: it is treated as an Effect Monster Card (Aqua-Type/WATER/Level 10/ATK 0/DEF 3000). This card cannot attack. (This card is still treated as a Trap Card)
Metal Reflect Slime is considered to perform a Special Summon. It occupies a S/T Card Zone and a Monster Card Zone. If Slime has its effect negated, it returns to the S/T Card Zone and never becomes a Monster Card again (because it's not being activated again), remaining on the Field meaninglessly. If flipped face-down, it returns to the S/T Card Zone face-down (and is considered to be Set during that turn, so you cannot activate it during that turn). Its Original ATK and DEF are 0 and 3000 respectively. While Slime isn't face-up on the Field, it's only considered to be a Trap Card, such as while in the Deck or when sent to the Graveyard.
Then, we have Malevolent Catastrophe:
Activate only when your opponent's monster declares an attack. Destroy all Spell and Trap Cards on the field.
Catastrophe is activated upon Attack Declaration. It doesn't target neither the attacking monster or the Cards that it will destroy.
The last Trap Card in the Deck is Dark Illusion:
Negate the activation of a Spell Card, Trap Card, or Effect Monster's effect that targets a face-up DARK monster, and destroy that card.
Dark Illusion doesn't target. It the Card that it intends to negate is targeting other Cards aside from the DARK monster, you can still negate its activation with Dark Illusion. This Card cannot be used in response to the effects of already-active S/T Cards.
Finally, the Deck introduces some really classic Cards used by Marik, albeit indirectly. The first one is Mystical Beast of Serket:
Destroy this card if you do not control "Temple of the Kings". Each time this card destroys a monster by battle, the destroyed monster is removed from play, and this card gains 500 ATK.
Serket has a Continuous Effect that destroys it if you don't control a Card named "Temple of the Kings". It can be negated by Skill Drain. Then, it has a Continuous Effect that Removes from Play any monsters that this Card destroys in battle. Finally, it has a Trigger Effect that you activate at the End of the Damage Step, which increases Serket's own ATK.
The last Card from the Deck is Temple of the Kings:
The controller of this card can activate Trap Cards the same turn they are Set. If you control "Mystical Beast of Serket" and this card, you can send both to the Graveyard to Special Summon 1 monster from your hand, Deck or Extra Deck.
Temple of the Kings has two effects. The first one allows its controller to activate Trap Cards during the same turn that they are Set. Even though this virtually means that you can activate Trap Cards from your Hand, notice that you MUST set them first. So for example, if Dark Simorgh is face-up, you won't be able to use Trap Cards with this effect. The second effect is an Ignition-like effect. Sending the Cards to the Graveyard is a cost. You can Special Summon a monster from your Hand, Deck or Extra Deck. Monsters in the Hand or Deck aren't too complicated, as you can only Special Summon monsters that aren't Special Summon-only monsters or Nomi monsters. However, the Extra Deck is more interesting. You can Special Summon any Fusion or Synchro Monster that doesn't have any restriction on its Special Summoning. So you can Special Summon a monster like Ally of Justice Catastor or Ojama King, but you cannot Special Summon Gladiator Beast Gyzarus or Trident Dragion.
Note that Temple of the Kings has been added to the Forbidden Card List upon its release.
As a bonus track, let's look at a key Marik Card that wasn't included in the Structure Deck. I'm talking about Makyura the Destructor:
During the turn this card is sent to the Graveyard, the owner of this card can activate Trap Cards(s) from his/her hand.
One of my favorite Cards. Makyura has an unique effect, with an even more unique classification. Its effect is actually Continuous, but doesn't rely on Makyura staying in the Graveyard at all. As soon as Makyura is sent to the Graveyard, its effect "starts working", without using the chain. That means that if you send Makyura to the Graveyard as a cost for some effect, you can already start chaining Trap Cards from your Hand to that effect. Furthermore, if Makyura is removed from the Graveyard, such as with D.D. Crow, its effect still works. Makyura's effect is superior to that of Temple of the Kings, so it stays side by side to it in the Forbidden Card List.
Well, that covers all of Marik's Cards. Stay tuned for some Starstrike Blast Cards. If you have any questions, feel free to drop me an e-mail at ness00[at]gmail[dot]com.