Unlike text-changing effects, type-changing effects are pretty common. Most Modern players have likely dealt with the effect of Blood Moon or Spreading Seas a few times. This week we'll look at what makes types tick and how modifying them works.

I've Got a Type

To identify a card's supertype(s), type(s), or subtype(s), look at the typeline around the middle of the card, to the left of its set symbol. Everything to the left of a long dash is a supertype or type; anything to the right, a subtype. Each card type has its own set of subtypes, with two exceptions. Creatures and tribals share their subtypes, as do instants and sorceries.

For example, Gingerbrute is an Artifact Creature - Food Golem. Food is its artifact subtype, while Golem is its creature subtype. Go-Shintai of Shared Purpose is a Legendary Enchantment Creature - Shrine. Legendary is its supertype. It has two card types: enchantment and creature. Shrine is its enchantment subtype, and it has no creature type. (I've probably said "Shrine is not a creature type" a few hundred times since the Kamigawa: Neon Dynasty Shrines were spoiled.)

Supertypes

Magic has five supertypes. Legendary, snow, and basic are commonly used. Ongoing has so far only appeared on schemes, a card type in Archenemy supplemental products. The last new card printed with the world supertype is old enough to vote... that supertype hasn't been used since 1996!

Adding or removing a supertype from an object only affects that specific supertype. For instance, activating Arcum's Weathervane's first ability targeting Dark Depths makes Depths a legendary land; removing its snow supertype doesn't affect that legendary supertype at all.

Land Ho!

Modern favorites Blood Moon and Spreading Seas set lands' type to a basic land type. While their implications can seem obvious—"It's a Mountain now, so I can tap it for {R}"—there's a bit more going on under the hood.

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.

Magic Comprehensive Rules

We'll unpack that wall of text with some examples.

Dryad Arbor under a Blood Moon is still a green creature. But since it's a Mountain instead of a Forest, it taps for {R}, not {G}.

If I activate Inkmoth Nexus in response to a Blood Moon, it will be a Mountain that can tap for {R} and won't have its usual abilities. However, since settings its land subtype doesn't remove abilities from other effects, it'll still have flying and infect until end of turn.

If Dark Depths is in play and then Blood Moon enters, Dark Depths loses its usual abilities and can tap for {R}. However, this doesn't affect its supertypes, so it's still a legendary snow land. It works a little differently if Blood Moon is in play first. In that case, Dark Depths would enter with no counters on it. If Blood Moon were to leave play after that, Dark Depths would immediately trigger and unleash Marit Lage.

Urza's No Good Very Bad Day

Modern pillar Urza's Saga hates Blood Moon. Since Blood Moon makes it a Mountain, it loses all its usual abilities, but still retains the Saga subtype. It's now a Saga with no chapter abilities, meaning its final chapter number is 0. Any number of counters (even 0) on the Saga triggers the following rule:

715.4. If the number of lore counters on a Saga permanent is greater than or equal to its final chapter number, and it isn’t the source of a chapter ability that has triggered but not yet left the stack, that Saga’s controller sacrifices it. This state-based action doesn’t use the stack.

Magic Comprehensive Rules

So Saga is sacrificed immediately.

While the underlying mechanics are a little different (it's in layer 6, not layer 4), Alpine Moon has the same general interaction with Urza's Saga. The Saga loses all abilities, and therefore its positive chapter numbers, and so must be sacrificed.

...And Another Thing

Normally, setting a card's type to something makes it become just that type. For example, Song of the Dryads on Grizzly Bears makes the Bears just a land. However, as with many rules in Magic, there are exceptions.

205.1b Some effects change an object’s card type, supertype, or subtype but specify that the object retains a prior card type, supertype, or subtype. In such cases, all the object’s prior card types, supertypes, and subtypes are retained. This rule applies to effects that use the phrase “in addition to its types” or that state that something is “still a [type, supertype, or subtype].” Some effects state that an object becomes an “artifact creature”; these effects also allow the object to retain all of its prior card types and subtypes. Some effects state that an object becomes a “[creature type or types] artifact creature”; these effects also allow the object to retain all of its prior card types and subtypes other than creature types, but replace any existing creature types.

Magic Comprehensive Rules

Like the above lands rule, this one has several different things going on. Why isn't this broken up into separate rules? Who knows. So, let's dissect it ourselves!

Angelic Destiny enchanting Grizzly Bears makes the Bears a Creature - Bear Angel. Since Angelic Destiny makes it an Angel "in addition to its other types," it applies alongside the creature's normal type, not instead of it.

The same is true of a card like Destiny Spinner. If I target a Forest, it becomes a Land Creature - Elemental Forest. "It's still a land" makes it retain all previous land types and subtypes.

Facts About Artifacts

Making something an "artifact creature" has always been a special case, and we added a new one semi-recently with Throne of Eldraine.

Suit Up targeting Nyxborn Courser makes the Courser an Enchantment Creature - Centaur Scout until end of turn. Since Suit Up makes its target an Artifact Creature, it retains its card types and subtypes.

On the other hand, if I enchant the Courser with Darksteel Mutation, Courser becomes an Enchantment Creature - Insect. Since Darksteel Mutation specifies that the enchanted creature become an "Insect artifact creature," it overwrites any existing creature types.

Cleanup

We've now covered basic type interactions and looked at how some of the quirkier rules around them actually work. Next week I'll make a slight detour from the normal rules-heavy stuff. Join me then for some chatter about tournament policy!

As a reminder, feel free to reach out on Twitter or our Insider Discord with any questions.

Question of the week: What's an all-time-great type-changing effect? (I know it's not Arcum's Weathervane.)