Blood Moon vs. Urborg
Judge Level 1Urborg came later — and still loses. Dependency beats timestamps.
Cards involved
The setup
Your opponent controls Blood Moon ("Nonbasic lands are Mountains"). AFTERWARDS you play Urborg, Tomb of Yawgmoth ("Each land is a Swamp in addition to its other land types").
What happens?
Urborg has the later timestamp.
Are your lands Swamps now?
Pick an answer to continue.
Both effects work in layer 4 (type-changing). But Blood Moon's effect changes WHAT Urborg's effect does at all — it strips Urborg, a nonbasic land, of its abilities. That's a dependency: the effect being depended on applies first, no matter who has the later timestamp (613.8).
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.
The result
Urborg is a Mountain with no abilities; all nonbasic lands are just Mountains. Your Swamp plan is off.
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.
The contrast
Not every layer-4 meeting is a dependency: with Blood Moon + Spreading Seas on the same land, the timestamp really does decide — that case is part of the L2 batch.
Stack
Blood Moon
Nonbasic lands are Mountains
Urborg, Tomb of Yawgmoth
Each land is a Swamp in addition
The stack is empty.
Battlefield
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