Is Melee legal in Standard, Modern, and Commander?

Melee is legal in: Legacy, Vintage, Commander.

What type of card is Melee?

Melee is an Instant. Its oracle text reads: "Cast this spell only during your turn and only during combat before blockers are declared.You choose which creatures block this combat and how those creatures block.Whenever a creature attacks and isn't blocked this combat, untap it and remove it from combat."

Melee

Instant

Cast this spell only during your turn and only during combat before blockers are declared.<br>You choose which creatures block this combat and how those creatures block.<br>Whenever a creature attacks and isn't blocked this combat, untap it and remove it from combat.

Set Ice Age

Rarity Uncommon

Artist Dameon Willich