In the lead up to the 100th regular issue of the Defenders comicbook J.M. Dematteis and his cohorts created a long series of adventures, fairly skillfully woven together tighter and tighter.
The initial setup is that a series of supernatural adventures, guest starring sometimes long unseen Marvel Universe lesser characters, takes the Defenders through their paces, against a backdrop of the team having really bonded. They might not have had the Avengers charter and all the rest of the trappings but by this point the Defenders were a regular team in all but name- they hung out at Doctor Strange's brownstone in Greenwich Village, had a fixed roster, treated each other like a (dysfunctional) family, and so on.
Juxtaposed with this were classic Defenders in-fighting, Kraft and Gerber era style darkness and offbeat tales, and a deep sympathy with the late 60s and early 70s contrasting the (as yet unretconned) pasts of some of Marvel's monster magazine period characters with the changes in the general Marvel Universe.
Harking back to the Silver Age Marvel style, there were quotes from poems, pop culture references by the score, and some genuinely nasty supernatural elements.
The story arc also debuted a character destined to be added to the team and pushed to prominence for a short time- the Gargoyle!
All in all leading up to issue 100 it was good to see some sophisticated overlapping of stories for the first time in years. Opinion divides over whether the big reveal is big or credible enough a payoff...
The source of the recent supernatural threats is shown to be, not beings like Thog, who are involved, but in fact the entity from whom the lesser evils take their existence- SATAN!
Tired of seeing his son, Hellstrom, and his daughter, Hellcat, free and uncorrupted, Satan has contrived the whole involved plot- which included Strange unwisely using a teleportation spell which weakens reality, and many similar touches- to entrap his son and daughter and return them to their true destiny as scions of the netherworlds.
The story arc touches on a lot of dark aspects, including incest, sin, damnation, drug addiction, crazed doomsday cults with Jewish and Christian overtones- in a sense, classic Defenders. In another sense, it was the watershed- after this the Defenders either had to be another Marvel cookie cutter team destined for action figures and general audience entertainment or pretty much permanently get sidelined in the new corporatised reality of comics.