Blood Moon + Spreading Seas
Judge Level 2Two layer-4 effects on the same land — and this time the clock really does decide.
Cards involved
The aura arrives later
Your opponent controls Blood Moon — their own Mutavault is just a Mountain. You cast Spreading Seas ("Enchanted land is an Island") on the Mutavault.
What happens?
Both effects work in layer 4.
What is the Mutavault once Spreading Seas is attached?
Pick an answer to continue.
The difference from the Urborg case: Spreading Seas is an AURA, not a land — Blood Moon can't touch it, and neither effect changes what the other does. Without a dependency, layer-4 effects apply in timestamp order (613.7): first Blood Moon (Mountain), then Spreading Seas (Island). Both "set" the land type, replacing previous types.
613.7Within a layer or sublayer, determining which order effects are applied in is usually done using a timestamp system. An effect with an earlier timestamp is applied before an effect with a later timestamp.
The analysis
Always ask the dependency question first (613.8): does Blood Moon change what Spreading Seas does? No. The other way? No. → Timestamps. Spreading Seas is younger: the Mutavault is an Island (and can't animate itself anymore either, having lost its ability).
613.7Within a layer or sublayer, determining which order effects are applied in is usually done using a timestamp system. An effect with an earlier timestamp is applied before an effect with a later timestamp.
613.8Within a layer or sublayer, determining which order effects are applied in is sometimes done using a dependency system. If a dependency exists, it will override the timestamp system.
Layer-4 ping-pong
If a SECOND Blood Moon entered now, it would have the newest timestamp — the Mutavault would be a Mountain again. Without a dependency, layer 4 always belongs to the newest clock.
613.7Within a layer or sublayer, determining which order effects are applied in is usually done using a timestamp system. An effect with an earlier timestamp is applied before an effect with a later timestamp.
Stack
Blood Moon
Nonbasic lands are Mountains
Spreading Seas
Enchanted land is an Island
Mutavault
Your opponent's nonbasic land
The stack is empty.
Battlefield
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