Redirecting life loss vs redirecting damage

[Dragoon]

Hello,

For starter, the context is that we are using and developing a Treachery/Kingdom variant where each player has a special ability. One of our players on Discord asked us a question about a rules interaction that we didn't planned, and me and my co-developer cannot seem to agree on the interpretation of the card's text.

Here is the relevant rules text:

Until end of turn, if a source, spell, or ability an opponent controls would cause a Leader player to lose life, you lose that much life instead. The same is true for discarding cards and sacrificing permanents. (Damage causes loss of life.)

(Note: Leader just specifies one player in particular with the Leader identity, but the Leader type is not relevant in that specific case)

Now, the question is:

Let's suppose that we are playing EDH and that someone attacks the Leader player with their commander which isn't blocked. Before the combat damages are dealt, this ability is activated. What happens with the Commander damage?

Bonus question: What happens if the Leader player is attacked by an unblocked creature with Infect?

My interpretation is that the damages are still dealt, but the life loss resulting from the Commander damage are redirected towards the controller of the ability. The Commander damage are still "marked" though and if they amount to 21 or more, the Leader player loses. Infect doesn't cause life loss and so isn't affected at all by this ability.

His interpretation is that, as long as the damage causes life loss, they are entirely redirected and do not affect the Leader player at all, which implies that Commander damage will not be marked on the Leader player, but Infect still works fine.

Which one of us is correct? Or are we both wrong?

Thank you for your help!

[spacemonaut]

Let's suppose that we are playing EDH and that someone attacks the Leader player with their commander which isn't blocked. Before the combat damages are dealt, this ability is activated. What happens with the Commander damage?

We still track the Commander damage against the Leader, even if they're not losing life. Archon of Coronation says you can't lose life, but it also says:

Combat damage dealt to you by a commander is still tracked, even if it didn't cause you to lose life.

I think the best way to understand this would be to recognise that damage causes loss of life, but damage is not equal to loss of life. They are different events. The commander caused the damage. We track that. The damage in turn would cause loss of life. You're redirecting that loss of life, not the damage.

Bonus question: What happens if the Leader player is attacked by an unblocked creature with Infect?

Damage to a player from a source with infect does not cause loss of life. It creates poison counters. The ability you've described redirects loss of life, but there is no event of life loss happening. The Leader gets poison counters.

[Dragoon]

@spacemonaut: Your answer aligns to my interpretation of the rules. My friend's argument is that since the damages are responsible for the life loss, they are redirected before being dealt.

Basically, if I refer for example to the rule 120.4 in the comprehensive rules:

120.4 Damage is processed in a four-part sequence.

120.4a First, if an effect is causing damage to be dealt to a creature and that effect specifies that excess damage is dealt to another object or player instead, the damage event is modified to deal damage accordingly. Excess damage is damage greater than the creature's toughness, taking into account damage marked on that creature and other damage being dealt to it at the same time as this damage. Any damage greater than 1 is excess damage if the source dealing that damage has deathtouch.
120.4b Second, damage is dealt, as modified by replacement and prevention effects that interact with damage. (See rule 614, "Replacement Effects," and rule 615, "Prevention Effects.") Abilities that trigger when damage is dealt trigger now and wait to be put on the stack.
120.4c Third, damage that's been dealt is processed into its results, as modified by replacement effects that interact with those results (such as life loss or counters).
120.4d Finally, the damage event occurs.

He considers that the effect of our special ability takes place at 120.4b whereas I see it intervening after that, at 120.4c.

[spacemonaut]

120.4c directly calls out life loss and counters in the parentheticals, so if you're interacting with that, you're interacting with 120.4c.

Damage replacement being handled in 120.4b, separately from life loss replacement in 120.4c, explains how damage prevention prevents commander damage from being tracked, but "you can't lose life" doesn't prevent commander damage from being tracked.

Since you're developing the variant, it might be better to just discuss with your partner what you want the outcome to be. It would sure make sense to redirect commander damage and poison counters if that's what you want to do, and that just takes revising the ability: add "the same is true for damage" to that list. Otherwise, you've got a perfectly serviceable thing that prevents life loss but not those things.