"Slayers Evolution-R" is billed as the fifth season, but it's actually more like the second half of the fourth season -- it wraps up all the dangling plot threads and deals with the whole Taforashia disaster. And unsurprisingly, things get a lot darker in these episodes -- as you'd expect for the Slayerverse, things start lighthearted and goofy (soap opera!), but slowly become apocalyptic and explosive.
Lina and her friends focus their efforts on finding the Hellmaster's Jar, a magical item that transfers souls -- and currently holds the spirit of Rezo the Red Priest. With the assistance of a living suit of armor named Nama, the gang launches off into their latest quest... only to get tangled in a bizarre scheme of Zuuma's. He's sent Ozzel and the Hellmaster's Jar to a wealthy merchant named Radock, and lures Lina and Co. to the same town.
Of course, nothing is that simple: Radock isn't all he appears to be, monsters are attacking, and Xellos is trying to get his hands on the jar. However, getting the jar isn't the end of the Slayers' problems, especially since Pokota is determined to resurrect Rezo so the priest can restore his homeland of Taforashia -- and he trusts Rezo a lot more than the rest of the gang does. What is the Red Priest keeping hidden from them?
"Slayers Evolution R" pretty much does what the second half of every "Slayers" story arc does -- all the various loose plot threads (Ozzel, the jar, Taforashia) are tied up neatly, and Lina ends up getting roped into a potentially apocalyptic struggle that somehow stems from everything else in the plot. All that, and we get some nice nostalgia moments with Rezo and "Nama" (who seems strangely familiar to Amelia and Lina).
There's still plenty of hilarious stuff woven in, especially in the hilarious "soap opera" episode that mocks all the melodramatic stuff ("The shock of the accident's given me amnesia!" "I have amnesia too!"). But things get much darker after the gang encounters Zuuma again, resulting in some gruesome deaths, creepy monsters (hair tentacles!) and a horrific flashback where we see how poor Zelgadis became a chimera.
The biggest flaw is that the Epic Climactic Battle feels like a copy of a previous Epic Climactic Battle from way back in the first season. Seriously, come up with something new!
Lina is still bombastic and a little crazy, but she also seems more intelligent this time around, since she's apparently able to unravel people's nefarious plots. There's also fun episodes for Gourry (dumb and good-hearted) and Amelia (who gets stuck inside Nama), and poor Pokota is driven to desperate measures to save his people. And poor Zelgadis is forced to relive the horrors of his transformation into a chimera -- the scene where he finally confronts Rezo's soul is hauntingly powerful.
"Slayers Evolution R" isn't an independent season -- instead, it finishes up the stories begun in "Slayers Revolution," and winds up being a rollicking, dark-tinged adventure/comedy with a deja-vuey ending.