MTG Salvation

Wasn't sure where to ask this so figured here, in tournaments I know during a round when you play someone you can sideboard cards in between games however in between different rounds can you use a different deck since its another person or must you only use one deck from first round to last?

I've heard some people say naturalize can take out the theros god enchantments when how can that make sense. Before they are a creature isn't the enchantment still considered indestructible?

Scavenge allows you to put 1/1 counters equal to cards power on target creature, now when a creature goes to graveyard after being boosted , say a 1/1 giant growt&ed to 4/4 but dies that turn does that power of 4 stay with it in graveyard or is the power of a card only what's written on it not what it may have been boosted with either by instant sorcery or enchantment

How do you take something out that's indestructible especially when it comes to enchantments?

Oh crap your right nvm

Wow that's really good then ,ideally you want to do both but that's great for even just second effect

Let's say your creatures power And toughness is based on how many creatures are in graveyards which let's say is 4 , after a turn or two if that number goes to 6 will that then change the power and toughness to 6/6 or is it stuck at 4/4

If something like aetherling was told to be sacrificed if it is only creature can you exile to save it? If so what can't you exile out of, so if you have the land to exile its unkillable?

Yeah I'm sorry azorius charm

In theros these legendary enchantment creatures are only creatures if their bestow cost isn't less then five but they also are indestructible so now if they are just enchantments are they still indestructible?

Oh wow that's cool cause normally when a creature dies that's enchanted the enchantment also goes to graveyard right?

It says enchantment creature will become creature again when unattached to creature. But Ihow would it become unattached?