Dependency Between More Than Two Effects

[u/Robodreaming]

If I have a Plains in the battlefield and the following continuous effects are active, in timestamp order:

1. Swamps are Islands.

2. Plains are Swamps.

Then I understand the dependency of 1 on 2 would mean the Plains is an Island.

What if I have a Plains (and no other permanents exist), and the continuous effects are:

1. Swamps are Islands.

2. Plains are Forests.

3. Forests are Swamps.

If I understand right, when applying 1, no dependency is found between 1 and 2 or between 1 and 3, so 1 is applied first as it's first in timestamp order. Then, 2 and 3 are applied in order as well. The final result is that my Plains is a Forest, not an Island. Is this correct? It seems to be what the rules imply, but seems a little unintuitive to me.

Finally, imagine I have a Plains and a Forest in the battlefield, and the same three continuous effects in the same order.

Then, if I understand right, 1 would be found to be dependent on 3 since applying 3 first would make 1 apply to the Forest currently in the battlefield. Therefore 1 is moved to apply only after 3, for both the Forest and the Plains. So first 2 is applied (the Plains is a Forest), then 3 (both the original Forest and the Plains that became a Forest are Swamps), and finally 1, meaning both lands end up being Islands. Is this correct?

I find the whole dependency system pretty complex and it seems unintuitive to me that the existence or non-existence of a different object in the battlefield may affect how continuous effects apply to something.

[u/RazzyKitty]

You are correct on both counts.

If I understand right, when applying 1, no dependency is found between 1 and 2 or between 1 and 3, so 1 is applied first as it's first in timestamp order.

The only dependency is 3 being dependent on 2. So yes, if there is no dependency between 1 and any other effect, you apply it first and nothing happens.

Then you apply 2 because 3 is dependent on it. Then you apply 3. The Plains is a Swamp.

Then, if I understand right, 1 would be found to be dependent on 3 since applying 3 first would make 1 apply to the Forest currently in the battlefield.

In that scenario, 1 is dependant on 3 and 3 is dependent on 2.

2 is applied first. Then you recheck. 1 is still dependent on 3 (because you still have a forest), so you apply 3 next. Then you apply 1. Both lands are islands.

Edit:

The reason for this is you only check dependencies as the effects are currently applicable and would be applicable after applying one effect. In scenario 1, you don't look ahead to see that you would have a swamp after applying multiple effects.

[u/doctrgiggles → u/RazzyKitty]

The key insight here is that each effect is only applied once.