Is Mournwillow legal in Standard, Modern, and Commander?

Mournwillow is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Mournwillow

Q: What type of card is Mournwillow?

Mournwillow is a Creature — Plant Skeleton. Its oracle text reads: "Haste Delirium — When this creature enters, if there are four or more card types among cards in your graveyard, creatures with power 2 or less can't block this turn."

Creature — Plant Skeleton

Haste

Delirium — When this creature enters, if there are four or more card types among cards in your graveyard, creatures with power 2 or less can't block this turn.

Set Eldritch Moon

Rarity Uncommon

Mana Value 3

Artist Jeff Simpson

Collector # 187

Scryfall Gatherer