Is Seafloor Stalker legal in Standard, Modern, and Commander?

Seafloor Stalker is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Pauper, Historic.

What type of card is Seafloor Stalker?

Seafloor Stalker is a Creature — Merfolk Rogue. Its oracle text reads: "{4}{U}: This creature gets +1/+0 until end of turn and can't be blocked this turn. This ability costs {1} less to activate for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)"

Seafloor Stalker

Creature — Merfolk Rogue

: This creature gets +1/+0 until end of turn and can't be blocked this turn. This ability costs less to activate for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)