I have a few Questions about the use of Book of Moon.

1) Say Mobius or another Monarch is summoned, and I chain Book of Moon to flip him face-down. Does he still get his effect since when the chain resolves he is face-down?

2) If I activate Torrential Tribute when my opponent summons a monster, can he activate Book of Moon to flip it face down and then Torrential's effect disappears since there was no monster Normal summoned?

Any replies would be greatly appreciated, thanks.

1. Yes, Monarchs will still get their effect unless it specifically says that he must remain face-up on the field or is a Continuous Effect (which he is not).

2. No...the monster is still considered Normal Summoned...it was just flipped face-down by a card effect...that does not change anything except the fact that it is now face-down and now face-up.

The only thing it "counters" is Trap Hole, which targets or Bottomless Trap Hole which now can't "see" what its ATK is so that one monster can't be removed.

That depends on the order of the events... if I say, summon Neo the Swordsmaster in attack mode and activate Book of Moon targetting Neo (taking advantage of priority), my opponent can then activate BTH or Trap Hole and Neo would still be removed or destroyed.

I usually just go by the assumption that they summon, the opponent uses it and then they chain Book of Moon to it, lol (usually is the case)