Seems I got something backwards - I had a nice board, but wanted to clear my opponents creatures. Song of Freyalize kicked in and my dudes got indestructible until end of turn. Great, I thought, and threw down a Finality (all creatures get -4/-4 until end of turn. But who cares when you're indestructible for the same period of time, right?) All my creatures died. That's supposed to happen?

Yes. An indestructible creature can still die if its toughness is zero or less. A 2/2 after getting -4/-4 for example has a toughness of -2, which kills it. Comparatively if you attack with a 2/2 into an opponent's 4/4, you don't have a creature with toughness -2, you have a creature with toughness 2 that has taken four damage. Indestructible means it can't be killed regardless of how much damage it takes, so it stays alive.

Indestructible creatures can be deal by:
- Zero toughness
- Sacrifice
- Exile
We all learned that the hard way tho...

But look at the bright side:

It was probably hilarious for your opponent

If I'm remembering right you can slap a card on a creature that gives hexproof and strip it of other enchantments and auras already on it. Been a while so I'm not exactly sure my memory of the rules is correct but I'm pretty damn certain.
IF the way I remember it is the way it is, why when I play Shalai existing enchants an opponent has put on my creature are not stripped???
Now like I said my memory might not be exact as to how it works but I have a strong feeling I'm right so that makes my question very valid.

No, auras don't fall off a creature that subsequently gains hexproof.

So if you have a Nullhide Ferox, I can turn off his hexproof, cast Luminous Bonds, and then when the hexproof comes back, the Luminous Bonds would still be attached and he still can't attack or block.

Not sure why I remember it happening that way.
Ohhhh ****! I remember now. I'm thinking about Protection from a Color. Like casting a protection from white spell on a creature that had Pacifism on it. Pacifism would be removed.
Durp.
Nevermind.

Yeah, that did work differently.

Thanks. Another question that's been bugging me - sometimes my opponent knows one spell in my hand and can see it. But what if I have two of the same spell - does it matter which copy of the spell I cast, will it always appear to my opponent as I'm casting the single spell in my hand that he knew I had?

As far as I know, yes, it does matter which of the 2 copies you cast. When my hand is known to my opponent, I always keep new cards to my far right, so I know those are the ones not known. People have been asking for a "revealed" tag or something, who knows in the future that may be implemented.

No, at least it should not work this way. Don't ask for a source but the intention is to always play the known copy of two identical cards independent of which you click.

That's weird. Arena is supposed to be like paper magic, where you also have to make a choice? But good to know if that's not the case.