I want to write a sentence describing a mountain as serene and problematic, and also as dead and lively. I want the effect of having all four of those words, but they sound bad in a list one after another. How do I fix this sentence to be grammatically correct but still have the same effect of having serene/lively and dead/problematic linked to each other?

SENTENCE: "He journeys to a knoll in Oklahoma called Rainy Mountain, which he explains is a prominent landmark for the Kiowas that is both serene and problematic, dead and lively"

The only thing you can do now is use that sentence as a springboard. Make sure the following sentences give specific examples of what you mean by each of those four words.

It's not a comma splice. It's simply a way to connect adjectives in a particular way that draws attention to the parallels.

If that's not your thesis, then it should be later in the paper -- perhaps introducing the explanation of the seeming contradictions.

This leads into a later thesis that says the author views the mountain as representative of death and life. So i do expand upon what i mean by it.

Is it ok grammatically to say it is "serene and problematic, dead and lively"
or is that a comma splice? might just trash the sentence if it doesn't work right

To create a grammatically correct sentence while preserving the effect of having the contrasting words linked to each other, you can use parallel structure. You can achieve this by rephrasing the sentence as follows:

"He journeys to Rainy Mountain, a knoll in Oklahoma that the Kiowas consider a prominent landmark – a place that is both serene and lively, yet also problematic and seemingly lifeless."

In this revised sentence, the contrasting pairs "serene and lively" and "problematic and seemingly lifeless" are balanced using parallel structure. The sentence flows smoothly, maintaining the intended effect of contrasting the mountain's characteristics.