It won't turn any land into a basic land or remove the legendary supertype from a legendary land, and the lands won't be named "Island." If Harbinger of the Seas loses its abilities, it continues to turn nonbasic lands into Islands
In particular, though, it should be at the front of your mind during a draft, as it can guide you in the direction of good draft picks and an effective deck
Cards that dont require additional mana, like Sigardas Splendor and Cosmos Elixir solve this, but ultimately are a touch unreliable, especially in light of other card draw options in white
Put a +1/+1 counter on each creature you control
Taking inspiration from iconic comic covers and artwork, these cards are certainly eye-catching, but the text is a little too distorted or even too small on some of the cards, such as Electra, Daughter of the Hand, and Namor the Sub-Mariner
Brago, King Eternal probably still wears the crown when it comes to commanders for this archetype, letting you flicker your whole board every turn in most cases