Just replace "permanent" with "you".

I don't think there is a way to give an opponent shroud, or protection from a color. If there is, however, Mirror Shield, Your opponent having Protection from Blue and Oona's Grace says "Draw your library". It also says lose the game... but I'm assuming that, if you have the ability to give your opponent shroud, you probably have the Demystify ready to end it... especially after drawing your library. I suppose you could always use Ivory Mask and Donate to set this up, but that is a four card combo. Mind you, a four card combo utilizing three spells that are generally useful.

Otherwise, this card's kind of cool. I like the fact that some decks would play it, then play cards like Soothing Balm on themselves. Does my opponent get a 50% chance of gaining 5 life? Sure... but I'm playing combo or control and don't care about that. I, on the other hand, have a 25% chance of gaining 10 life, and a 25% chance of gaining 15 life or more when I do that.

As fun as it sounds, you can't go infinite with ricochet. Since it only creates a copy when a player casts a spell or activates an ability, creating a copy from a triggered ability doesn't create a second copy. The discussion on Mirror Spirit should clear up why.

In a duel, this merely reflects the spell onto your opponent. In multiplayer, the randomness kicks in.

Oh, yes, you're right about the copies not making copies. Good Show.

As for it always hitting your opponent in a duel... I'm not sure about that. It says to choose a 'new' target. But, in my head, that just means to put a new target on the stack and all targets are valid. If it asked you to choose a 'different' target, however, then it would have to hit the opponent. Would it make more sense to replace the word 'new' with 'different', if only to clear up the confusion?

If I said "different," would I still need to say "It can't target you"?

Ah. There's the sneaker hiding at the end. Well, you're right about that. I'll let you figure out which you prefer after that point.

What's it meant to do on things that say "target opponent" like Appetite for Brains (assuming a standard 2-player duel)?

Since you control the copy, it targets your opponent.

Oh, of course. What about a random targeted spell when the opponent has shroud (Leyline of Sanctity, Witchbane Orb etc)?

My issue is that I think this is the only card that can potentially create copies of spells with no legal targets. You're creating a copy of Oona's Grace that can't target you and (if the opponent has shroud) can't target the opponent either. What happens to it? (Okay, in practice I guess the answer is "it gets countered on resolution"...)

aha! I knew there was somewhere that "Cannot be countered" made problems :)

The problem here isn't "can't be countered"; if it somehow ended up making a copy of an uncounterable spell with no legal targets, the spell would resolve and do nothing to the illegal target. The problem is creating a copy of a spell without ensuring it has some legal target first.

If there's no legal targets, I think the triggered ability itself gets countered and no copy is made.