66. Swamp Thing and Friends vs. The Soul of Darkness (American Gothic)
The conclusion to American Gothic deals with the “Soul of Darkness” which is basically a Primordial Shadow, which threatens to change the status quo in Hell by marching upon Heaven.
John Constantine puts Swamp Thing into the position where he can help stop this, in a two-front battle.
Swamp Thing and a host of notable DC magic users (like Phantom Stranger, Dr. Fate and Etrigan the Demon - who is leading an army of demons who don’t WANT the status quo to change) into battle with the Shadow and his army of demons.
Meanwhile, back on Earth, Constantine leads a group of the most notable magicians in the DC Universe to also stop them. In the ensuing magic battle, both Sargon the Sorceror and Zatara are killed.
Ultimately, it all comes down to Swamp Thing (as Constantine planned it), who convinces the Shadow that evil and good are not necessarily at odds with each other - the Shadow then strikes up a balance with the Light of Heaven, and all is right with the world (except for the casualties, of course).