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Judge tips – Characteristic-defining abilities

I want to take some time to talk about a rules concept that seems to confuse me – Characteristic-Defining abilities (CDA).

What is a CDA? Well, according to CR 604.3, some static abilities are characteristic-defining abilities. A characteristic-defining ability conveys information about an object’s characteristics that would normally be found elsewhere on that object (such as in its mana cost, type line, or power/toughness box) or overrides information found elsewhere on that object. CDAs function in all zones. They also function outside the game.

So let’s look at a card example.

Woodland Changeling

Ok, so as we look at the card’s text box we see “Changeling (This card is every creature type.)”

This is a simplistic example. With the textbox specifically indicating a change to the creature-type of the creature.

But what about Sera Avatar?


It sure is. Why? Because a part of the text box that states, “Serra Avatar’s power and toughness are each equal to your life total.”

This ability conveys information about the creature’s power and toughness. Plus, it functions in all zones.

Now let’s take a look at Rakdos Keyrune’s second printed ability. It says, “BR: Rakdos Keyrune becomes a 3/1 black and red devil artifact creature with first strike until the end of turn”


So here we have an activated ability granting a static ability to the keyrune. This isn’t an intrinsic ability and this means it’s not a CDA.

How do we know this? Well, we need to look at 604.3a

A static ability is a CDA if it meets the following criteria: (1) it defines an object’s colors, subtypes, power, or toughness; (2) it is printed on the card it affects, it was granted to the token it affects by the effect that created the token, or it was acquired by the object it affects as the result of a copy effect or text-changing effect; (3) it does not directly affect the characteristics of any other objects; (4) it is not an ability that an object grants to itself; (5) it does not set the values of such characteristics only if certain conditions are met.

Writing this, it strikes me that CDAs really aren’t that difficult. You just need to pay attention. Or, as we judges like to say, RTFC!

That’s it for this week! Check back for more judge tips next time!

Patrick Cossel is the publisher of the Forge Herald and a Magic Judge (L1). Professionally he is the Operations Manager of a family owned newspaper company. He is married and has two boys. He can be contacted at pcossel@gmail.com


© 2016, Patrick Cossel. All rights reserved.

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About Patrick Cossel,

I am a journalist and gaming enthusiast.

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