It keeps things safe by only allowing one cast per tap
[1] The cascading player may cast that nonland card without paying its mana cost
Mono White Devotion is a midrange combo deck where you are trying to control the battlefield with enchantment removals like Baffling End and Stasis Snare which also turn on the Devotion for Heliod, Sun-Crowned while actively presenting a combo kill with Walking Ballista
Either way, after the madness card is cast and leaves the battlefield, it goes to the graveyard like a normal card
That includes all the Un sets, Portal and other Starter sets, and stuff like the Global Series, Secret Lairs, and more
I know it seems straightforward, but the waters can get muddy