Modal double-faced cards can be turned face down while on the battlefield

[PurpleCrowbar]

In Xmage, if a player controls [[Tergrid, God of Fright]] (a modal double-faced card), and an [[Ixidron]] enters the battlefield, Tergrid is incorrectly turned "face down" and becomes a 2/2 with no abilities. The rule is that double-faced cards should not be able to be turned face down while on the battlefield (e.g. due to the effects of Ixidron, see this article), but can enter the battlefield face down as a result of being manifested (see this article).

The expected result of an Ixidron entering the battlefield should be that Tergrid, as a double-faced card, is unaffected by Ixidron's ability.

[github-actions[bot]]

Tergrid, God of Fright // Tergrid's Lantern - (Gatherer) (Scryfall) (EDHREC)

{3}{B}{B} Legendary Creature — God 4/5 Menace Whenever an opponent sacrifices a nontoken permanent or discards a permanent card, you may put that card from a graveyard onto the battlefield under your control. :arrows_counterclockwise: {3}{B} Legendary Artifact {T}: Target player loses 3 life unless they sacrifice a nonland permanent or discard a card. {3}{B}: Untap Tergrid's Lantern.

Ixidron - (Gatherer) (Scryfall) (EDHREC)

{3}{U}{U} Creature — Illusion / As Ixidron enters the battlefield, turn all other nontoken creatures face down. (They're 2/2 creatures.) Ixidron's power and toughness are each equal to the number of face-down creatures on the battlefield.

[PurpleCrowbar]

It seems like Ixidron functions as expected with TDFCs (e.g. [[Delver of Secrets]]), but specifically fails with MDFCs like Tergrid. Updating title

[github-actions[bot]]

Delver of Secrets // Insectile Aberration - (Gatherer) (Scryfall) (EDHREC)

{U} Creature — Human Wizard 1/1 At the beginning of your upkeep, look at the top card of your library. You may reveal that card. If an instant or sorcery card is revealed this way, transform Delver of Secrets. :arrows_counterclockwise: Creature — Human Insect 3/2 Flying