Help with dependencies

Asked by filledelanuit 9 years ago

I recently passed my rules advisor exam and missed a question that involved a dependency. Could you please help me clarify my understanding of dependencies.

  1. What is a dependency?

I believe it is when two effects occur in the same layer, or sublayer, and on modifies the effect of another.

  1. How do you determine which effect to apply first?

  2. If I control a Thespian's Stage that has copied a Urborg, Tomb of Yawgmoth and my opponent controls a Blood Moon , what is everything?

Thanks for the help

Epochalyptik says... #1

A dependency occurs when two effects would apply in the same layer/sublayer, and one would modify the existence of the other. You always apply the independent effect first.

In your example, everything would be a Mountain. Urborg, Tomb of Yawgmoth 's effect is dependent on Blood Moon 's effect because that effect removes Urborg, Tomb of Yawgmoth 's.

June 24, 2014 6:20 p.m.

Rhadamanthus says... #2

For effects in the same layer/sublayer, if either both or neither effect is from a characteristic-defining ability, then if one effect modifies the other's text, existence, what it applies to, or how it affects what it applies to, the second effect is said to be "dependent" on the first (and the first is called "independent"). In this relationship, the independent effect is always applied first. If both effects are dependent on each other (a "dependency loop"), then they're applied in timestamp order instead.

June 24, 2014 6:39 p.m.

filledelanuit says... #3

Correct me if I am wrong but, if some of the abilities of an object have been applied and it then loses its abilities you still apply them as though they still existed. ex. Why Humility and Opalescence care what the timestamp order is.

If that is true then wouldn't all nonbasic lands be mountains and swamps and all basic lands be their original type and swamp. Or does it not apply here because the copy effect from Thespian's Stage only modifies itself not another objects.

June 24, 2014 7:19 p.m.

Rhadamanthus says... Accepted answer #4

It's not that abilities are applied "as though they still existed". They're applied in layer order, meaning Opalescence 's type-changing effect is applied before Humility 's ability-removing effect. That is, Opalescence's ability still exists at the time it would be applied, so it is. If that ability gets removed in a later layer you don't rewind the process and un-apply it. The only reason the two cards care about timestamp order when interacting with each other is because they both have a P/T setting effect, and that's the only part of their respective abilities you apply timestamp order to.

For your examples:

  • Layer 1: Copy effects. Thespian's Stage is instead an Urborg, Tomb of Yawgmoth .
  • Layer 2: Control-changing effects. Nothing going on here.
  • Layer 3: Text-changing effects. Nothing going on here.
  • Layer 4: Type-changing effects. Both the Thespian-Urborg and Blood Moon would apply in this layer. Because of the rules about what happens when a land gets a basic type that isn't "in addition to its other types", applying Blood Moon would change the existence of T-Urborg's effect, so T-Urborg is dependent on Blood Moon. Blood Moon's effect is applied first, which means T-Urborg's effect doesn't exist at the time it would be applied. Nonbasic lands are mountains.
  • Layer 5: Color-changing effects. Nothing going on here.
  • Layer 6: Ability granting-removing effects. Nothing going on here.
  • Layer 7: P/T modifying effects. Nothing going on here.
June 24, 2014 11:24 p.m.

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