MTG Salvation

Yes, both players have to pass priority in the End Step before the game will proceed with cleanup and advancing to the next turn. If he casts Murder during the opponent's endstep, the point where Demonic Rising would have triggered has already come and gone.

In this case the trigger never even goes on the stack, because the intervening if clase is not satisfied. Even if it did go on the stack though, he can still let it resolve and then will get priority again before the turn advances to the next step.

You can stop the Academy Rector's ability by removing the card from the graveyard. Its ability is a triggered ability, nothing happens until it resolves. Because it contains the "If you do" clause, the search can't happen if there's nothing there to exile.

With the exception of some premier events, such as the Blue Envelope at a PTQ, prize distribution is entirely up to the TO/person supplying the prizes. There is no DCI policy, judges are not required to get involved or help you sort it out, other than to investigate for potential Bribery. The TO could decide you're both shady and give everything to second place if they wanted. Not a good business move perhaps, but it's not DCI's issue.

An actual DCI infraction for unsportsmanlike conduct has to be issued during the tournament.
The owner of the store can ban someone from the store/events in the store for any reason they like, that is also not a DCI issue.

You are correct, the back "counts" for EDH:

903.4c The back face of a double-faced card (see rule 711) is included when determining a card’s
color identity.
Example: Civilized Scholar is the front face of a double-faced card with mana cost
{2}{U}. Homicidal Brute is the back face of that double-faced card and has a red color
indicator. The card’s color identity is blue and red.

Yes, Deathtouch applies to all damage dealt by a creature.

All targets must be declared when the spell or ability is put on the stack. If none of the targets are legal anymore when the spell resolves, it is countered (fizzles).

1) Yes, that's fine, you can cast Ancestral Visions by means which allow to to be cast 'without paying its mana cost.'

2) nothing interesting happens. Rebound specifically only triggers "when cast from your hand."

You are correct. When Dead Weight leaves the graveyard the first time, it becomes a new game object. It becomes a new game object yet again when it returns to the graveyard. The second Sun Titan trigger to resolve will not find the game object that it targeted and fizzle.

Maddening Imp yes, the imp's ability will destroy creatures that didn't attack for any reason.

Or do you mean he played the creatures after you had already used the ability? Those would be safe then. The set "Non-wall creatures active player controls" is determined at the time the ability resolves and "those creatures" does not expand to include any that arrive later.

"Cast the copy" means to put it on the stack and follow the normal procedure for casting any other spell like you would if it were a card in your hand, (without paying the mana cost in this case)

It is true Stifle would be required to stop the ability of Isochron Sceptre, but once the sceptre's ability resolves, the copied card is now a spell on the stack that can be targeted by Counterspell just like any other spell.

You cannot act before the trigger to remove the last time counter from Lotus Bloom goes on the stack, but Lotus Bloom itself won't go on the stack until that trigger resolves and takes off the last counter. You can respond to your Suspend trigger with a Silence and it will resolve before you have to put Lotus Bloom itself on the stack later.

Characteristic Defining Abilities (such as those two) are always looking at whatever it is they check/count and reflecting the current value. Their P/T is actually that value all the time. If Lord of Extinction where in the GY with 5 other cards and you had an ability that said "return a card with power 6 to your hand" you could use it on him.

Quote from Atrius

Yes, if the card said "When you successfully cast", you would not as successfully cast means it needs to resolve. That is not the case for Kozilek.

The same applies for the Shrine, you only need to cast white spell to add a counter, it doesn't need to resolve.

The first sentence is not correct. No card currently has 'successfully cast' in its text. The oracle text needs to be checked for the current wording. Triggered abilities printed that way are errata'd to "When(ever) ~ cast", although not everything originally written "when successfully cast" is currently handled as a trigger.

Blinking won't save your creature. It will go away and come back all while Slagstorm is still on the stack. Then Slagstorm resolves and deals 3 damage to it.

Gaining Protection from Red will save your creature form Slagstorm, because Slagstorm kills by dealing damage and damage is one of the things Protection saves you from.

Nope. If you Cloudshift in response to the Clone on the stack, your creature comes right back and is still there to be copied as Clone enters the battlefield.

If the clone does copy your legend, they both go to the graveyard immediately as a state based action. Nobody gets priority to play and spells or abilities in between the choice to copy and the state based actions.