They share some kind of theme between them flavor, a mechanic, creature type, or play well together
Heartless Summoning is the inverse (creature spells cost two less), but thats not the effect were going for here
Sentry Oak | Illustration by Warren Mahy This isnt really a broken space, as the only ways to get around the restriction on walls and defenders attacking are printed on cards that explicitly let you do that
That will not be this deck, although a few cards here and there will likely populate given both care about attack triggers and both share two colors
Making a couple of 1/1s with trample is cute, but not terribly impressive
Creatures (28) 4 Thassa, God of the Sea 4 Master of Waves 4 Stratus Dancer 4 Gudul Lurker 4 Shorecrasher Elemental 4 Faerie Miscreant 4 Harbinger of the Tides Lands (25) Spells (7) Sideboard We might not have nice things like Cloudfin Raptor, but Faerie Miscreant is a pretty solid upgrade over Hypnotic Siren or Triton Shorestalker