Rules Tip of the Day: Unless specified, activated abilities can only be used by the controller of the permanent or card with the activated ability.

Q: If I'm playing a game and my opponent has the only enchantment in play when he brings Nikko-Onna into play, is he obligated to destroy his own enchantment? Or is it a choice instead of an effect?

A: When Nikko-Onna comes into play, its ability will trigger. When this ability goes on the stack, your opponent must choose a target if there is one available, he is not given the option of ignoring this ability. So yes, he must destroy the enchantment he controls.

Q: I have two Skull Collectors in play, and no other creatures. During my upkeep, can I put the ability of one the Collectors in the stack targeting the other Collector then returning it with the other Collector's ability? In short, can I keep a Skull Collector in play?

A: No. Skull Collector's ability does not target anything. When this ability resolves, you return a black creature that you control to your hand. The ability of each Skull Collector will trigger independently at the beginning of your upkeep, and you can not manipulate the situation and satisfy both effects by returning just one black creature to your hand.

Q: Can Horobi, Death's Wail's ability be countered by Squelch or Bind when it activates, stopping it before the victim creature is destroyed?

A: No, Horobi's ability is a triggered ability, not an activated ability. In order to counter Horobi's ability you would need to use Stifle.

Q: If I reanimate a Platinum Angel while I'm at 6 (or less) life, do I lose, since I pay the life before the Angel is in play?

A: No, you will not lose at that point. State-based effects will not be checked until after the Reanimate has completely resolved. And while your life total may be below zero at that point, you will control the Platinum Angel, so you will not lose.

Q: I've got a question about Reprocess. Is the "Sacrifice any number of artifacts, creatures, and/or lands..." part of the casting cost (like the life-payment of Hatred) or do I sacrifice them on resolution (like the sacrificing of mountains for Landslide)?

A: Reprocess is similar to Landslide. You do not sacrifice any permanents until Reprocess resolves. This means that if the Reprocess is countered, you will not sacrifice anything. If you had to sacrifice permanents as an additional cost it would specifically state that you make this sacrifice "As an additional cost."

Q: If you pay 2 to make Chimeric Sphere a 2/1 flier, then block a flier, would it still be legal to pay 2 more and make it a 3/2 without flying?

A: Yes, you can do that. Normally when a permanent is reanimated it does not lose any abilities it has. However, Chimeric Sphere's second ability specifically states that it becomes a creature without flying, so the resulting creature will be a 3/2 without the flying ability.

Q: Can you Maze of Ith an attacking Akroma, Angel of Wrath (or anything else with vigilance)?

A: Yes. The only targeting requirement on Maze of Ith's ability is that you target an attacking creature. The word "untap" in that ability is an instruction to untap this creature when the ability resolves. If this creature it not tapped, then this portion of the effect will be ignored.

Q: How will my Invoke Prejudice affect opponents if all I control are artifact creatures? What about if I control no creatures? If there's no colored creature permanents to share colors with, is there no effect?

A: If all creatures you control are colorless, then any creature spell your opponent plays will not be able to share a color with a creature you control; your creatures do not have any color to share. This means that your opponents will have to pay mana equal to the converted mana cost of this creature spell when Invoke Prejudice's ability resolves, or the spell will be countered. This will also occur if you do not control any creatures, as your opponent's creature spell can't share a color with something that does not exist.

Q: I have a Triskelion (with three +1/+1 counters), Mephidross Vampire, and a copy of Mephidross Vampire, made by Kiki-Jiki, Mirror Breaker. One at a time, and letting them resolve individually, I do a point of damage to my Triskelion, netting a +1/+1 counter each time. Say I put 100 counters on it and then remove a counter, and respond to that by removing a counter, and do this untill all the counters are gone. My question is how much damage would resolve? Just 3, due to the Triskelion dying from the 100 points of damage I dealt to it? Or would they all resolve, since they were put on the stack?

A: You'll only be able to deal three points of damage, because you won't be able to activate the Triskelion's ability 100 times—just three. Each time you active the Triskelion's ability, state-based effects will be checked. After the third activation, the Triskelion will be a 97/97 creature with 97 points of damage on it, and it will go to the graveyard.