Confirmed The Book of Exalted Deeds and Blood Moon/Spreading Seas

[wheels47]

1. Activate Book of Exalted Deeds, targeting a creature land like Mutavault
2. Play Blood Moon after
3. Blood Moon now incorrectly causes the Mutavault's "You can't lose the game" static ability to be ignored

Can also be reproduced with a card like Spreading Seas.

The example I provided is from a single-player game, but the bug exists in multi-player games too.

 

[Torbin]

Tag that needs to be applied: Can Not Reproduce
Testing applied: Tried to reproduce the game state by halo testing around the steps as explained by the reporter.
Test Results: Mutavaults "You cant's lose the game" ability functions as normal.

 

[Neo001992]

I was able to reproduce this. I died immediately after Bloom Moon resolved even though the counter on the land should be independent of if the land is a mountain just like how the counter is independent of the angel being an angel or not.

Edit: This is correct behavior since the ability is not linked to the counter being added to the land. Because the ability is granted to the land and is not being given by the counter placed (this is why you don't assume things), Blood Moon correctly removes the ability that was granted to the land when it was an angel.

• The enlightenment counter placed by the last ability serves as a memory aid. It isn't connected to the granted ability. The Angel keeps that ability even if it loses the counter. Similarly, if the counter is somehow moved to another permanent, that permanent doesn't gain the ability.(2021-07-23)
• Nonbasic lands will lose any other land types and abilities they had. They will gain the land type Mountain and gain the ability "{T}: Add {R}."(2020-08-07)

https://imgur.com/a/Hs39sfY

Event#273754305 Game#898089558

 

[Toxic Stench]

• Nonbasic lands will lose any other land types and abilities they had. They will gain the land type Mountain and gain the ability "{T}: Add {R}."(2020-08-07)

If you check the CR you will see this reminder means "land types and [land] abilities", not all abilities. Mutavault should keep the ability granted by The Book.

305.7. If an effect sets a land’s subtype to one or more of the basic land types, the land no longer has its old land type. It loses all abilities generated from its rules text, its old land types, and any copiable effects affecting that land, and it gains the appropriate mana ability for each new basic land type. Note that this doesn’t remove any abilities that were granted to the land by other effects. Setting a land’s subtype doesn’t add or remove any card types (such as creature) or supertypes (such as basic, legendary, and snow) the land may have. If a land gains one or more land types in addition to its own, it keeps its land types and rules text, and it gains the new land types and mana abilities.

 

[Neo001992]

If you check the CR you will see this reminder means "land types and [land] abilities", not all abilities. Mutavault should keep the ability granted by The Book.

You are correct good sir. Even found a JudgingFtW video covering this exact interaction upon looking around more.

 

[wheels47]

Tag that needs to be applied: Can Not Reproduce
Testing applied: Tried to reproduce the game state by halo testing around the steps as explained by the reporter.
Test Results: Mutavaults "You cant's lose the game" ability functions as normal.

Here is another example from a two-player game, but with Harbinger of the Seas instead of Blood Moon. I incorrectly lose the game when Mutavault's ability should prevent me from losing the game. Match 273635888 Game 897619498