This does require Frank to attack each turn, which isnt always ideal, but his indestructible trigger helps a lot with this
Take a look: Weirdly, this particular rambling McNally has never seen a reprint, so any copy out there that you might see is forever just Creature Construct. As per official rulings, it is indeed an artifact, if you couldnt tell by the frame, the colorless casting cost or the general animated map-ness of it all
But with Marnie, the versatility, disruption, and engine-like qualities of her card make her so much more of a threat
However, as shes Floodborn, she also has Shift
Because the spell is an Aura spell, its controller must choose a legal target for that spell as defined by its enchant creature ability and rule 601.2c
[G][C][C][C] Seismic Toss: 130 damage