This card works passively too: If you mill five cards and three are lands, youll put them all onto the battlefield
The biggest knock against Unsettled Mariner is the fact that it is likely difficult to find room for multiple copies, but the ability to protect your creatures (and yourself) from spells your opponents cast is potentially quite valuable
More than likely though, youll be splashing into more than one colour with common identities being Izzet (blue and red), Grixis (blue, black, and red), Azorius (white and blue), and Esper (white, blue, and black)
I would take Korlessa, Scale Singer and Mirror Box out for them
The lone blemish that the mechanic has is the existence of Alrund's Epiphany, and while that card maybe shouldnt have foretell printed on it, its intrinsically powerful enough that the mechanic isnt entirely to blame
Multiple Lavabrink Venturers with different odd/even choices no longer visually stack while on the battlefield
