Greetings, Judges! Let me apologyze for posting this week's scenario so late, we've had a logistic problem.
Welcome back to another exciting Knowledge Pool scenario. This week we have Bronze scenario, so judges who have judged more than a couple Competitive REL events should wait until Sunday before they reply.

http://blogs.magicjudges.org/knowledgepool/?p=2015

You are the HJ of a Modern PPTQ. At the beginng of round 2, you ask your floor judge, James, to help you in a deck check. While doing the deck check James asks you “What do you think about this card? Isn't it marked?” and he handles you an altered Blood Moon. The art of the card has been extended to the borders making the card distinguishable when the top of the sleeves are facing you. The card is marked and can't be played, so you ask the owner of the deck, Andrew, to replace it with a non-marked one after explaining him he has committed TE-Marked Cards. Andrew will be assessed a Warning for his infraction.

Andrew doesn't have a replacement for the Blood Moon but chooses to play an Island instead, and you fix the deck list to match the current deck. At the end of round 3, Andrew finds you and tells you he's traded a non-marked Blood Moon and wants to play it instead of the Island.

What do you do?

I get to do my first CompREL event tomorrow, so I'll take a whack at this.

I would inform Andrew that since he decided to replace the altered Blood Moon with a basic Island, his choice has been made and he cannot revert that choice. This is addressed in the MTR:

3.11 Marked Cards

If a player is required to replace a card in his or her deck and is unable to find a replacement, the player may
replace the card with a basic land card of his or her choice. Once the player does this, he or she may not revert
back to the original configuration, even if the player finds an acceptable replacement. This also applies to cards
that are lost.

Originally posted by Mitchell Nitz:

I get to do my first CompREL event tomorrow, so I'll take a whack at this.

I would inform Andrew that since he decided to replace the altered Blood Moon with a basic Island, his choice has been made and he cannot revert that choice. This is addressed in the MTR:

Mitchell you may want to check the version of the MTR you quoted.

Current MTR:
http://wpn.wizards.com/sites/wpn/files/attachements/mtg_mtr_15oct02_en.pdf

Current IPG
http://wpn.wizards.com/sites/wpn/files/attachements/mtg_ipg_02oct15_en.pdf

From IPG 3.8:

. If the player is unable to find replacement cards, he or she may replace those cards with basic lands; this change may be reverted at a later point if replacements for marked cards are found.

I would tell Andrew that is fine and wish him the best of luck.

Originally posted by Jared Mallett:

From IPG 3.8:

. If the player is unable to find replacement cards, he or she may replace those cards with basic lands; this change may be reverted at a later point if replacements for marked cards are found.

I would tell Andrew that is fine and wish him the best of luck.

Would you do any other things?

Originally posted by Christopher Wendelboe:

Jared Mallett
From IPG 3.8:

. If the player is unable to find replacement cards, he or she may replace those cards with basic lands; this change may be reverted at a later point if replacements for marked cards are found.

I would tell Andrew that is fine and wish him the best of luck.

Would you do any other things?

I suppose I should check that the new Blood Moon is indeed non-marked, then I would also ask him to revert any changes made to the decklist.

Originally posted by Jeff S Higgins:

Mitchell Nitz
I get to do my first CompREL event tomorrow, so I'll take a whack at this.

I would inform Andrew that since he decided to replace the altered Blood Moon with a basic Island, his choice has been made and he cannot revert that choice. This is addressed in the MTR:

Mitchell you may want to check the version of the MTR you quoted.

Current MTR:
http://wpn.wizards.com/sites/wpn/files/attachements/mtg_mtr_15oct02_en.pdf

Current IPG
http://wpn.wizards.com/sites/wpn/files/attachements/mtg_ipg_02oct15_en.pdf

I will have to do that. I was pretry sure i had updated my links to the IPG and MTR since BFZ came out. I see the change in what was quoted by others so as soon as I am home I'll update my links (important for review for tomorrow apparently!)

From the IPG, Section 3.8 (Tournament Error - Marked Cards):

If the player is unable to find replacement cards, he or she may replace those cards with basic lands; this change may be reverted at a later point if replacements for marked cards are found.

Let Andrew play with the unmarked Blood Moon in his deck, and change the decklist to reflect this.

Edited Matt Cooper (Nov. 15, 2015 06:46:55 AM)

I'm in agreement with Matt. I would thank him for adapting to the situation and update his decklist back to it's original configuration.

Pretty much what everybody else said–As per recent change to IPG, we can revert the decklist change, allow him to replace the basic island with the newly acquired blood moon (provided it is not also marked), Remind him in the future that he needs to check alters with the head judge of EVERY event before round one, and wish him luck in the rest of his matches.

Greetings Judges, it's time to wrap this up!

This week's scenario was inspired by a recent update in the IPG.

Additional Remedy
…
If the player is unable to find replacement cards, he or she may replace those cards with basic lands; this change may be reverted at a later point if replacements for marked cards are found.

We allow Andrew to revert the change and play the Blood Moon again since this clause has been added to IPG. We also revert the change in the deck list so that it matches the deck again.

Thanks for participating in this week's scenario and see you soon in another exciting scenario!