Is Dwarven Sea Clan legal in Standard, Modern, and Commander?

Dwarven Sea Clan is legal in: Legacy, Vintage, Commander.

Dwarven Sea Clan

Q: What type of card is Dwarven Sea Clan?

Dwarven Sea Clan is a Creature — Dwarf. Its oracle text reads: "{T}: Choose target attacking or blocking creature whose controller controls an Island. Dwarven Sea Clan deals 2 damage to that creature at end of combat. Activate only before the end of combat step."

Creature — Dwarf

: Choose target attacking or blocking creature whose controller controls an Island. Dwarven Sea Clan deals 2 damage to that creature at end of combat. Activate only before the end of combat step.