Uba mask scenario

[oneofchaos]

As opposed to complicating the game state as it was, I can reduce it without anything having any difference.  My opponent and I are both out of cards, he has 10 x 10^999 life, he an uba mask and I have a 1/1 attacker.  What exactly happens?  Can I just say I win due to the game state will never ever change as there are no cards in hidden zones and nothing in the graveyard that will matter?

[Anusien]

You can demonstrate to the judge that you have a loop.  If you say, "I'm going to attack every turn", you create a loop where the game state is the same each turn except that your opponent has 1 less life.  You can then loop to the end of the game, unless your opponent has an effect to interrupt it.

[Clariax]

If you can demonstrate some loop, which in this case attacking repeatedly turn after turn while nothing else is happening (including never drawing a card), you can then say you're going to repeat that loop X times (X likely being 10x10^999).  Your opponent can either accept the loop, or if he wishes to interrupt it at some point, he may do so.  He can pick whatever point he wishes, whether it's after the first attack, or the upkeep of the 1000th turn, or whatever.  What he absolutely CANNOT do, however is say something like "I want you to play it out."  To not accept such a loop in this situation would be a pretty clear attempt at stalling, and should be penalized as such (i.e. call a judge).

[oneofchaos]

Similarly if I control possessed portal, opponent and I are out of cards in our decks, and I have a squee + 1/1 attacker, I may demonstrate a loop?

[Wagner]

That would work but you would need 2 Squees. Your opponent will still be able to stop the loop at any time if he can (ESG + Oxidize to win).

Possessed Portal
If a player would draw a card, that player skips that draw instead.
At the end of each turn, each player sacrifices a permanent unless he or she discards a card.