Buffy Season 8, Vol. 4: 'Time of Your Life' by Joss Whedon and Jeff Loeb
Volume 4 of Buffy S8, Time of Your Life, is so full of wasted potential. A book where Buffy meets future Slayer Fray should be exciting more than wonderful. There have been complaints that readers have to read the spin-off Fray comics to understand parts of Time of Your Life, but Fray was written before S8, and is a good comic that all Buffy fans should consider reading.
The problem is that Time of Your Life contains no indication that Fray is an interesting character. Here, she's angry, fights with Buffy, and speaks in incomprehensible future slang, even though she was perfectly understandable in her own series. Basically, she's portrayed as a thug; there's no sign of the multi-dimensional Fray who stole food for orphans and was alternately cold and vulnerable towards her family.
Buffy and Fray spend most of their interactions fighting with each other or tensing up for a fight, but it comes off as empty, hollow conflict because they don't have many philosophical or personal differences. Buffy was on rough terms with Kendra and Faith because they approached slaying differently than she did, but both Fray and Buffy value friends and family and fight vampires in order to protect them. The only real differences between them are the way they dress and the way they speak. None of their conflicts result in character development or shed light on who they are as people.
Meanwhile, Willow's magic goes from awesome to creepy and exploitative. It turns out that in order to gain the knowledge to bring Buffy back from the future, Willow has to perform a magic ritual where she has sex with a woman and gets mentally transported to an alternate dimension at the moment of climax where she meets a giant snake-lady who is also her lover. The scene is non-explicit, but it comes off as crass instead of romantic or sexy, and why is Kennedy okay with Willow having sex with a giant snake?
Even worse, for Willow's character, the main point of Vol. 4 is that in the future, all of the magic in the Buffyverse will be destroyed except for vampires, and that Willow will be trapped in perpetual torment as someone who has just enough magic to be immortal but not enough to cast major spells. Future Willow brings Buffy into the future for the sole sake of ending her life with her enchanted axe. It's a horrible and disappointing end for a beloved character, and opens up a plot hole of why Future Willow couldn't have just asked Fray to kill her with her own axe.