Today I'm interested in talking about cards that flip your opponent's monsters facedown. Now why would you want to do that when you could play Raigeki, Dark Hole, or Interrupted Kaiju Slumber? Board wiping is okay, but it's relatively unsuited to today's meta/popular card pool. I actually don't play any copies of board wipes in the decks I play competitively at the moment. I'm also not talking about cards like Book of Moon, which is a one-for-one targeting flip. It could honestly go to 2 or 3 without any trouble, but I don't really want to get into the Forbidden & Limited List either (please free Super Polymerization, I'm totally not a Metalfoes player). I'm instead, looking to talk about the cards Book of Eclipse and Swords of Concealing Light. These are cards that a lot of you might or might not already be playing, but you should at least know why or why you aren't, not just copying it from someone's decklist!
What do these cards do, exactly?
Let's first consider why these cards are good? Just by reading either card, you'd be hard pressed to find the word "target" on either. They also do not destroy your opponent's monsters, something that many decks and monsters have an answer to (Return of the Dragon Lords, immunity to destruction, gaining advantage because of floating after destruction, etc.) Non-targeting, non-destruction threat management is extremely strong at the moment with plenty of important non-targetable monster threats including Majespecter Unicorn - Kirin, the Kozmo big ships, Dante, Pilgrim of the Burning Abyss, and dragons granted immunity by Azure-Eyes Silver Dragon. When either of these spells resolve, you are able to take the non-targetable immunities of these monsters out of the equation. There are also a good deal of "trap monsters," or monsters with disruptive quick effects that can be baited out or turned off by being flipped facedown. Some of these monsters include Beatrice, Lady of the Eternal, Blue-Eyes Spirit Dragon, Kirin, and the upcoming ABC-Dragon Buster. Forcing your opponent to use a trap monster effect in a non-ideal situation or completely miss out on an opportunity to use a trap monster's effect puts you in a good position to make a push play, or establish board presence. Both cards also serve as an out to floodgate monsters, which must be face-up for their continuous effects to apply. Blue-Eyes Spirit Dragon, Jowgen the Spiritualist, Vanity's Fiend, and other cards of the like can't do much to you as long as you can't see their card art.
The Pen vs. the Sword(s)
So with the utility of these two cards laid out, which one should you be using if you were convinced? While the end result of activating Book of Eclipse or Swords of Concealing Light is fairy similar, there are certain nuances. The most glaring difference is the type of spell each card is. Book of Eclipse is a quick-play spell, while Swords of Concealing Light is a continuous spell. This means that Swords can be prevented from resolving or turned off by spell/trap removal while Eclipse cannot be. Shouldn't that mean that the clear favor goes to Eclipse? Not quite, Eclipse puts you on a timer, because at the end of the turn it was activated all of your opponents monsters are flipped face-up and they draw a card for each. If you are unable to deal with their board, you're giving them free card advantage. If Swords is able to resolve, the monsters that it flips face down are unable to be manually flipped face-up until two of your standby phases after the card's activation or it leaves the field. If Swords is unanswered, it gives you more time to generate a response to a particularly packed board, without directly giving your opponent advantage.
The difference doesn't end there, the monsters that the card flips facedown are also nuanced. Swords of Concealing Light only flips monsters that were present on the field at the card's activation. If, say, Blue-Eyes Spirit Dragon were to tag out in response to Swords, whatever monster it tags out into will not be flipped facedown. If Book of Eclipse were activated instead, any monsters on the field at it's resolution will be flipped facedown, whether they were there or not at Eclipse's activation. While Swords tends to be a more permanent flipping, it is able to be disrupted, and can be dodged to an extent. The fact that Eclipse is a quick-play that has a wider blanket is really quite important. Being a quick-play, you can activate it during your opponent's turn to stop plays that they might've intended to make before they even get to a problem monster. You can stop a BA/PK player from making any plays period by turning their board into a toxic wasteland, while also reacting to their terrortop or telegraphed Phantom Knight normal summon. You can also stop Mermail Atlanteans from pushing for an OTK on you or even paying cost for Neptabyss, the Atlantean Prince's effect. You might cringe at the idea of giving your opponent cards, but a deck like Metalfoes might not particularly care if there are a bunch of low-defense monsters on the board. I was able to brute-force more than a few games at regionals by using an off-turn Eclipse and then summoning Metalfoes Orichalc + 1 or 2 Metalfoes monsters for game via double piercing damage.
Final Words
I tend to lean towards Book of Eclipse in my deck building for the current meta because it suits my deck's weaknesses and allows me to push for game in ways that I'm not normally able to. While what I lean towards shouldn't dictate what you play, I strongly suggest you look into playing/testing one of the two cards for yourself. I'm sure you'll find them quite useful! Thanks, as always for reading and good luck dueling!
