Such an effect, for example, the effect of "Dark Cat with White Tail", targets the monsters it will return. If there aren't enough valid targets, then the effect won't even activate. It is not legal to activate an effect if it can't resolve fully.
This is different to legally activating an effect and then conditions changing before it resolves - that's handled on a card to card basis. In the above effect, if it was activated legally but something was chained that removed a target from the field, the effect will resolve as much as it can, returning the other targets to hand.
If the opponent has no monsters in deck, or no monsters that Last Turn can special summon, then they just don't get a monster, nothing happens in the additional battle phase, and the opponent will probably lose in the end phase.
Since both monsters are your opponent's weakest monsters, you get to pick which one your Fissure destroys.
Your opponent's Windstorm of Etaqua changes the battle positions of all face-up monsters you control, then your Creatue Swap swaps your monster and your opponent's monster, since Creature Swap's effect only says that those 2 monsters can't change their battle positions for the rest of the turn, so the position change before the swap is legit.
The priority will always go to the monster that was Summoned first and has remained on the field. Therefore, the monster that was Summoned first will remain unaffected and the monster that was Summoned second will have its effect negated along with the other monsters on that side of the field.This ruling is similar to the Jinzo vs. Skill Drain debate. Whichever card was active first, has priority over the other.For confirmation on this ruling, click on the "Related Link" below and look at "Skill Drain" under the "Mentions in other Rulings" of the "TCG Rulings" section.
If your opponent attacks, you can activate Book of Moonto flip the attacking monster face-down and cancel the attack. However, if you chain the activation of Book of Moon with Dark Mirror Force (assuming your opponent has a face-down Defense Position monster WHEN he/she attacks), the attacking monster will not be affected by Dark Mirror Force as a chain always resolves BACKWARDS. Therefore, Book of Moonwould be Chain Link 1 and Dark Mirror Force would be Chain Link 2. When resolving, the effect of Dark Mirror Forceactivates first, removing your opponent's Defense Position monsters (this does not include the attacking monster as it must be face-up and in Attack Position to have attacked in the first place) from play. Then the effect of Book of Moon resolves, flipping the attacking monster face-down. Note that you could not even activate Dark Mirror Force unless your opponent has a Defense Position monster to begin with.Assuming the same scenario, if you decide to activate Dark Mirror Force FIRST, then Book of Moon (targeting the attacking monster), then Dark Mirror Force would become Chain Link 1 and Book of Moon would become Chain Link 2. Again, the chain would resolve backwards, starting with the effect of Book of Moon. Your opponent's attacking monster is flipped face-down first. Then the effect of Dark Mirror Force resolves, Removing from Play all of your opponent's Defense Position monsters, including the original attacking monster (as it is now in Defense Position).
If the opponent has no monsters in deck, or no monsters that Last Turn can special summon, then they just don't get a monster, nothing happens in the additional battle phase, and the opponent will probably lose in the end phase.
As per Soul Exchange's effect, one of the monsters for Amazoness Archer's cost can be one of the opponent's monsters.
Since both monsters are your opponent's weakest monsters, you get to pick which one your Fissure destroys.
If the opponent's monster is in attack mode, then both monsters are destroyed. If it's in defence, then nothing happens.
What happens is you choose a monster on your opponent controls. Then you choose monsters in your graveyard to remove from play. But you have to remove monsters from play equal to the Level of your opponent's monster. Then your opponent's monster that you chose is destroyed. Eg. If you wanted to destroy Giant Rat, then you would have to remove 4 monsters in your graveyard from play because Giant Rat is Level 4.
A card cannot be activated, if it can't fully resolve. It is usually ok to activate a card legally and have it still resolve as fully as it can if the game state changes before resolution. But for example, you can't activate Creature Swap if one player doesn't have a monster, you can't activate Fissure if the opponent has no monster. Even if all you want is the attack negation part of Super Junion Confrontation, you cannot activate it unless you've got a monster for it to affect. So the situation would be an illegal one, you could not activate it.
Dragunity Aklys has a triggered effect when it is destroyed while equipping one of your monsters. This triggered effect targets and destroys one card on the field. If the opponent's side of the field is empty, then you must target one of your own cards instead. If there are no valid targets at all, the effect simply fails to activate.
Like Dark Necrofear vs Last Turn, the monsters will battle, and Interplanetary Invader 'A' will be desroyed by battle. You will then take control of the opponent's monster. When Last Turn's victory condition is checked, you will control a monster and the opponent will not, meaning you won. The original owner of the monster doesn't matter, only who controls what at that moment in time.
The Wicked Avatar's own effect always takes precedence over any other effect that tries to modify or set its ATK. Mirror Mail's effect will be disregarded and The Wicked Avatar will have an ATK equal to the opponent's monster +100.
That would not be legal. Starlight Road has to chain directly to the card it will be countering. That means if you activate a destruction effect and the opponent chains their Starlight Road, you can't use yours.
Your opponent's Windstorm of Etaqua changes the battle positions of all face-up monsters you control, then your Creatue Swap swaps your monster and your opponent's monster, since Creature Swap's effect only says that those 2 monsters can't change their battle positions for the rest of the turn, so the position change before the swap is legit.
Dragon Ruler monsters have a triggered effect that activates in the opponent's end phase, to return themselves to hand if they were special summoned. This trigger can be negated by the usual means. You could activate the trigger, chain Forbidden Chalice, then Forbidden Chalice will make it so the trigger will be negated when it resolves, the Dragon Ruler will stay on the field for another turn.