Dominaria was the games first set on Magics home plane in 12 years, since the Time Spiral block that concluded in 2007
Omen was introduced in Tarkir: Dragonstorm where it appears on wild dragon cards
Plus, any copies of Overlord that get Milled then come back as big threats once you resolve Superior Spider-Man as a copy of Bringer
Instead of relying on just the characters and conflicts to drive the lore and flavor, the expansion is effectively a multi-decade tribute to a larger pop-culture phenomenon
Hence, you could activate the ability of Wall of Roots in between turns, and as it wasn't during a turn, you could activate it as many times as you wanted
I always said both of these cards being in white was probably the greatest unintentional political statement Magic ever did, showing both sides were "good", from a certain perspective