Some basics, and some rather obscure things. Even some things I submitted to them myself. ^_^
06/11/15 rulings:
Q: If I have no face-up Attack Position monsters on my side of the field, can I conduct my Battle Phase?
A: A player cannot enter their Battle Phase during the first turn of the Duel, but during a later turn, even if the turn player has no face-up Attack Position monsters on their side of the field, they can still conduct their Battle Phase.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=271&keyword=&tag=0
Q: If a monster is Normal or Special Summoned in face-up Attack Position, or Flip Summoned to face-up Attack Position, does it have to attack?
A: Even if there is a face-up Attack Position monster in the turn player’s Monster Zone, the turn player can choose arbitrarily whether or not to conduct their Battle Phase. That player can end their turn without conducting their Battle Phase, or also enter their Battle Phase without declaring any attacks with their monsters.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=260&keyword=&tag=0
Q: During their Battle Step, if the turn player wants to declare an attack with their monster, can their opponent activate any cards or effects before an attack can be declared?
A: The turn player is always the first one to be able to activate a card or effect or to take an action during any Phase or Step. Even if the non-turn player wishes to activate a card or effect, the turn player can do so first in order to proceed with the turn. In this scenario, since the turn player can make the first action during the Battle Step, it is not possible for their opponent to activate a card or effect before the turn player is able to declare an attack. However, the Battle Phase begins with the Start Step before proceeding to the Battle Step. (It is not possible to declare attacks during the Start Step.) Therefore, during the Start Step, the opponent is able to activate cards and effects before any monsters can declare attacks.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=239&keyword=&tag=0
Q: Can the effect of Pyro Clock of Destiny be applied to the effect of Doom Virus Dragon?
A: The effect of Doom Virus Dragon is one that counts turns, so the effect of Pyro Clock of Destiny can move its turn count forward.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=16182&keyword=&tag=0
Q: If my opponent has Umi and The Legendary Fisherman on their side of the field, can my Vennominaga the Deity of Poisonous Snakes attack The Legendary Fisherman?
A: In this situation, because the effect of The Legendary Fisherman is being applied, it cannot be targeted for attack. (This effect is not one that affects an attacking monster.) Therefore, Vennominaga the Deity of Poisonous Snakes cannot attack The Legendary Fisherman, but if there are no other monsters on your opponent’s side of the field, it can attack your opponent directly.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=16181&keyword=&tag=0
Q: I have both Toon Kingdom (in my Field Zone) and Toon World (in my Spell & Trap Zone) face-up on my side of the field. If Toon World is destroyed by my opponent’s Mystical Space Typhoon, and I have Toon Mermaid and Toon Dark Magician Girl face-up on my side of the field, can I apply the effect of Toon Kingdom which allows me to banish a card from the top of my Deck instead of destroying my Toon monsters?
A: Even in this scenario, you can apply the effect of Toon Kingdom. In this case, since Toon World was destroyed, the effects of Toon Mermaid and Toon Dark Magician Girl that destroy them will be applied at the same time. If you want to apply the effect of Toon Kingdom, you can choose whether or not to apply it for each of those Toon monsters.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=16180&keyword=&tag=0
Q: Necrovalley is face-up on the field. In this situation, if a Level 7 or lower “Red-Eyes” monster on my side of the field is destroyed by my opponent’s attack or card effect, can I activate the effect of a Red-Eyes Tracer Dragon in my hand?
A: Even while the effect of Necrovalley is applying, you can activate the effect of Red-Eyes Tracer Dragon in your hand. In that case, since the effect of Red-Eyes Tracer Dragon would remove a card from the Graveyard, the entire effect is negated. (Red-Eyes Tracer Dragon remains in the hand without being Special Summoned, and the destroyed “Red-Eyes” monster also remains in the Graveyard without being Special Summoned.)
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=16179&keyword=&tag=0
Q: During my opponent’s turn, if I activate the effect of Escalation of the Monarchs, can I Tribute Summon The Winged Dragon of Ra – Sphere Mode?
A: If you activate the effect of Escalation of the Monarchs during your opponent’s Main Phase or Battle Phase, you can Tribute Summon The Winged Dragon of Ra – Sphere Mode. In that case, if you are Summoning it to your side of the field, you must Tribute 3 of your monsters, and if you are Summoning it to your opponent’s side of the field, you must Tribute 3 of your opponent’s monsters.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=16178&keyword=&tag=0
Q: I have Precious Cards from Beyond face-up on my side of the field. If I Tribute Summon The Winged Dragon of Ra – Sphere Mode by Tributing 3 of my opponent’s monsters, will the effect of Precious Cards from Beyond activate?
A: In this situation, even though The Winged Dragon of Ra – Sphere Mode is Tribute Summoned to your opponent’s side of the field, the controller of Precious Cards from Beyond was the one who performed the Tribute Summon, so the effect of Precious Cards from Beyond will activate.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=16177&keyword=&tag=0
Q: When resolving the effect of Super Junior Confrontation, how does the Battle Phase proceed?
A: Super Junior Confrontation is activated when an opponent’s monster declares an attack. After the attack of that monster is negated, damage calculation is performed between your opponent’s face-up Attack Position monster with the lowest ATK and your face-up Defense Position monster with the lowest DEF. Afterward, apply any effects that resulted from the battle, such as those that activate after damage calculation, at the end of the Damage Step, or when a monster is destroyed by battle, etc., as with a normal battle. After all the effects that activate in the Damage Step finish resolving, the Damage Step ends and it becomes the End Step of the Battle Phase.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=195&keyword=&tag=0
Q: When my Battlin’ Boxer Glassjaw declares an attack, my opponent activates the effect of Scrubbed Raid. If I then chain Last Counter, how do the effects resolve?
A: In this scenario, the effect of Last Counter will make you enter the Damage Step and perform damage calculation. In this case, the effect of Scrubbed Raid will not apply.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=242&keyword=&tag=0
Q: Field Barrier is face-up on the field. In this case, when my opponent Special Summons a monster, can I activate Demise of the Land?
A: In this situation, since the effect of Field Barrier is applying and preventing Field Spell Cards from being activated, Demise of the Land cannot be activated.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=223&keyword=&tag=0
Q: If Demise of the Land is activated, how many Spell Counters are placed on Skilled Blue Magician?
A: In this scenario, a Spell Counter is not placed on Skilled Blue Magician for the Field Spell Card activated by the effect of Demise of the Land. Therefore, only 1 Spell Counter will be placed on Skilled Blue Magician for the activated Demise of the Land.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=228&keyword=&tag=0
Q: Can I activate the effect of Red-Eyes Wyvern during my opponent’s End Phase?
A: If you have not Normal Summoned/Set this turn, you can activate the effect of Red-Eyes Wyvern during your own End Phase. You cannot activate the effect during your opponent’s turn.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=212&keyword=&tag=0
Q: If a Set card is targeted with Dark World Lightning, can Judgment of Anubis be chained to it?
A: If a face-down Defense Position monster is targeted with Dark World Lightning, Judgment of Anubis cannot be activated in a chain. If a face-down card in the Field Zone or Spell & Trap Zone is targeted with Dark World Lightning, Judgment of Anubis can be activated in a chain.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=165&keyword=&tag=0
Q: When my opponent adds 2 WATER monsters with 1500 or less ATK from their Graveyard to their hand with the effect of Salvage, can I activate Return?
A: Even if your opponent adds 2 cards from their Graveyard to their hand with the effect of Salvage, you can activate Return. In that case, the player that activated Salvage chooses 1 of the 2 cards added to their hand by its effect and shuffles it into the Deck, and the effect of Return finishes resolving. (Note that the remaining card that was added to the hand remains in the opponent’s hand.)
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=9681&keyword=&tag=0
Q: Can Fire Formation – Tenken be activated by targeting a Beast-Warrior-Type Normal Monster?
A: Fire Formation – Tenken can be activated by targeting a Beast-Warrior-Type Normal Monster. In that case, the targeted monster is still unaffected by other card effects during this Main Phase, and gains 300 ATK as long as Fire Formation – Tenken remains face-up on the field.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=7839&keyword=&tag=0
Q: While I have a Performage Trapeze Magician face-up on my side of the field, I declare an attack on an opponent’s monster during my Battle Phase. In this case, if my opponent activates Magic Cylinder, can I still chain the effect of Performage Flameater in my hand?
A: While the effect of Perfomage Trapeze Magician is applying, whenever you resolve an effect that would inflict damage to you that is equal to or less than the ATK of Performage Trapeze Magician, that damage becomes 0. In this scenario, the effect of your opponent’s Magic Cylinder is considered a card effect that would inflict damage to you. Therefore, you can activate the effect of Performage Flameater in a chain to your opponent’s Magic Cylinder.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=254&keyword=&tag=0
Q: While I have a Des Wombat face-up on my side of the field, if my opponent activates Ceasefire, can I still chain the effect of Performage Flameater in my hand?
A: While the effect of Des Wombat is applying, you take no damage from card effects. In this scenario, the effect of your opponent’s Ceasefire is not considered a card effect that would inflict damage to you. Therefore, you cannot activate the effect of Performage Flameater in a chain to your opponent’s Ceasefire.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=269&keyword=&tag=0
Q: When a face-down Defense Position monster on my side of the field is targeted for an attack, can I activate Gamushara?
A: Even if a face-down Defense Position monster on your side of the field is targeted for an attack, you can activate Gamushara. Also, by changing your monster to face-up Attack Position, it will be flipped face-up, so the effects of Flip monsters, Geargianchor, etc. can be activated normally.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=9118&keyword=&tag=0
Q: Can Berserk Scales be activated during the Battle Step or Damage Step by targeting a monster that is attacking directly?
A: Berserk Scales cannot be activated by targeting a monster that is attacking directly. Note that Berserk Scales can target a monster that already attacked directly during this Battle Phase.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=151&keyword=&tag=0
Q: If Butterflyoke is treated as an Equip Card, can it be equipped to a different monster using Tailor of the Fickle?
A: No, it cannot.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=8819&keyword=&tag=0
Q: When my Queen Dragun Djinn attacks an opponent’s monster, can I activate the effect of Muzurhythm the String Djinn during the Damage Step?
A: Since Queen Dragun Djinn is an Xyz Monster with “Djinn” in its name, you can activate the effect of Muzurhythm the String Djinn in this scenario.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=8731&keyword=&tag=0
Q: Can Mini-Guts be activated by targeting a face-up monster that I own but my opponent controls?
A: Yes, it can. Although the ATK of that monster becomes 0 until the end of this turn, if that monster is destroyed by battle, it will be sent to your own Graveyard, so the effect of Mini-Guts that inflicts damage will not activate.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=230&keyword=&tag=0
Q: If the effect of Forbidden Lance is applied to an Xyz Monster equipped with Xyz Unit, so that it becomes unaffected by Spell effects, how will each effect of Xyz Unit be applied?
A: If the effect of Forbidden Lance is applied to an Xyz Monster equipped with Xyz Unit, the equipped monster will no longer gain ATK equal to its Rank × 200. Even in that case, the effect of Xyz Unit will still allow you to activate the effect of the equipped Xyz Monster by detaching Xyz Unit instead of one of its Xyz Materials.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=7838&keyword=&tag=0
Q: A monster is Special Summoned face-up by the effect of Monster Reborn, and then changed to face-down Defense Position by Book of Moon. If Special Hurricane is activated in this scenario, will that monster be destroyed?
A: In this scenario, even if a monster that was Special Summoned by the effect of Monster Reborn is changed to face-down Defense Position by the effect of Book of Moon, since it is still treated as a Special Summoned monster, it will be destroyed when the effect of Special Hurricane resolves.
http://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=5&fid=213&keyword=&tag=0
