I am a usual reader of the site Cranial Insertion wherein they post and discuss the FAQs of the cards in every new set of Magic: the Gathering. I have learned a lot from them and which have helped me pass my Judge Level 1 exam last January. I think it would be good to share some of the Q and A here, quoting from the one of their blog posts.
To start:
Q: If I cast Tormenting Voice and for some reason it has rebound, for example because of Narset Transcendent, will I have to discard a card when it rebounds?
A: Yes. Rebound only gets you out of the mana cost of the spell. You still have to pay any additional costs to cast the spell, or pay for any cost-increasing effects which would apply to it.
Q: If I give Temporal Trespass rebound with Narset Transcendent, will it rebound?
A: No, it won’t. Rebound only creates the delayed trigger for casting the card again if the spell would go to the graveyard at the end of its resolution. Since the card exiles itself, the “cast it again” trigger won’t get created.
Q: Can I give a spell with rebound a second instance of rebound with Narset Transcendent?
A: You can, but it won’t do any good. Once the first instance of rebound replaces the card’s trip to the graveyard with a trip to the exile zone, the second instance of rebound no longer applies because the card is no longer going to the graveyard.
Q: Can Ultimate Price kill a face-down creature?
A: No, it can’t. “Monocolored” means having exactly one color, and colorless is not a color. A colorless creature has no colors at all, which is exactly one color short of being monocolored.
Q: Let’s say I control a manifested Dragonlord Dromoka and during my turn my opponent casts a spell I don’t like. Can I turn Dromoka face up in response to counter the spell?
A: I’m afraid not. You can turn Dromoka face up in response, but your opponent’s spell has already been cast by the time you can respond. Dromoka’s ability stops your opponent from casting more spells, but it won’t stop the spell he already cast from resolving, and it won’t counter the spell.
Q: When I cast one of the Commands, in which order do the chosen effects happen?
A: The effects always happen in the order in which they’re printed on the card, even if you want the effects to happen in the reverse order for some reason. Note that the cards are designed with that rule in mind, so you’ll usually want the effects to happen in their printed order.
Q: Can I control both Dromoka, the Eternal and Dragonlord Dromoka at the same time?
A: Yup, that’s not a problem. Unlike the planeswalker uniqueness rule that looks at the planeswalker type, the legend rule looks at the full card name. “Dromoka, the Eternal” is a different name than “Dragonlord Dromoka,” so the two versions manage to coexist without throwing the multiverse into a catastrophic time travel paradox.