They are avoiding giving us the exact rarity, as they did with The One Ring, because that data point unlocks a whole lot of additional information for us: number of packs, how many copies of a card exist, things like that
Samut takes full advantage of this, granting other creatures the player controls +X/+0, where X is their current speed, as well as making non-creature spells cost X less to cast, where X is their current speed
Sensational Spider-Man Sensational Spider-Man is already cool as a 3/3 that taps creatures with a stun counter
Can I put an Aura on an opponents creature
It also comes with the Family Blessings ability, which, once per turn, lets you put the top card of your deck facedown in your inkwell exerted when you remove one or more damage from one of your characters