Is Firemaw Kavu legal in Standard, Modern, and Commander?

Firemaw Kavu is legal in: Modern, Legacy, Vintage, Commander.

Firemaw Kavu

Q: What type of card is Firemaw Kavu?

Firemaw Kavu is a Creature — Kavu. Its oracle text reads: "Echo {5}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.) When this creature enters, it deals 2 damage to target creature. When this creature leaves the battlefield, it deals 4 damage to target creature."

Creature — Kavu

Echo (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)

When this creature enters, it deals 2 damage to target creature.

When this creature leaves the battlefield, it deals 4 damage to target creature.

Set Time Spiral Remastered

Rarity Uncommon

Mana Value 6

Artist Greg Hildebrandt

Collector # 163

Scryfall Gatherer