Casting an opponent's commander

Question: In the Commander game format, is it possible to construct a situation where you can cast an opponent's commander from the command zone?

Of course the answer is "yes" (and the image below spoils the answer), but the interesting rules question is why it's possible.

One way to achieve that is to make the opponent's commander go to the top of that opponent's library (for example with Excommunicate), and then attack with an unblocked Daxos of Meletis. After that, even if your opponent decides to put the commander in the command zone instead of exiling it, you can nevertheless cast it.

This is a little quirk of the rules of the game (and is in fact something that WotC fully acknowledges as a valid thing to do. In fact, a recent rules change clarifies the situation, making it even clearer.)

The key reason why this is possible is because the effect uses the wording "that card", rather than for example "the exiled card". (For example the same would not work with something like Oblivion Ring, which says "when Oblivion Ring leaves the battlefield, return the exiled card to the battlefield under its owner's control." Because it uses that wording, if the card is not in exile when the ability resolves, it won't do anything. This is delineated in the rules of the game.)

Because Daxos uses the wording "that card", if the exiling is replaced with the card going to another public zone, the effect will keep track of it (until it changes zones to somewhere else, after which it loses track of it because it's now a different object.) Note that it won't be able to track it if the exiling is replaced with going to a hidden zone.

So the next logical question is: What about the commander mana tax? Do you have to pay 2 extra mana for each time it has been cast from the command zone?

You don't pay the owner's mana tax. Instead, you have your own mana tax imposed for that particular commander (and which is independent from the mana tax of your own commander.) In other words, the first time you do this, there is no tax. However, if you manage to repeat the same feat with the same commander during the same game, you'll now have to pay 2 extra mana to cast it (and so on.)

Damage replacement and redirection

Suppose you control a Force Bubble and a planeswalker (it doesn't matter which for the intents of this question; I'm putting Jace in the image just as a random example). Your opponent casts a damage spell, like Lightning Bolt, targeting you. Question: Is it possible for your opponent to redirect that damage to the planeswalker or not?

An intuitive answer would be that "of course not; the Bubble is replacing the damage with something else, so there's nothing to redirect to the planeswalker." However, it's not that simple. This is actually a bit contrived part of the game.

The Bubble's ability is a replacement effect. The redirect-damage-to-planeswalker rule is also a replacement effect (this is defined so in the rules of the game. It doesn't really matter that the replacement effect is optional, it still applies here.) Thus there are two replacement effects trying to modify the same damage. So what happens?

The rules state in this case that the affected player (ie. in this case you) decides the order in which the two replacement effects are applied. Thus you have two options:

If you decide that the Bubble's effect is applied first, then the damage is replaced with putting counters onto the Bubble. After that the planeswalker-redirection effect does nothing because there's nothing to replace anymore.

However, you could also choose to have the redirection effect apply first (in most cases this wouldn't be sensible, but in some cases it could well be.) What happens then?

The effect in question now asks your opponent whether he or she wants to redirect the damage to the planeswalker. If your opponent does, then the damage is redirected, and then Bubble's effect does nothing (because likewise there's nothing to replace anymore).

However, if your opponent does not want to redirect the damage, now the Bubble's replacement effect is applied, and in this case there is something to replace, so the damage is replaced with putting counters on the Bubble.

So this is an interestingly contrived situation. To recapitulate, these are all the options:

1. You decide to apply Bubble's effect first. The damage is replaced with counters on the Bubble, and the other effect then does nothing.
2. You decide to apply the redirection effect first. Now your opponent chooses whether to redirect the damage to the planeswalker or not.
   1. Your opponent decides to redirect, thus the planeswalker gets the damage and nothing else happens.
   2. Your opponent decides not to redirect. Then the Bubble's replacement effect is now applied, and it takes place.