Avernus was one of the evil Planes, right?
And the Blood War?
That really doesn't sound like good place* to start a adventure. Unless you're starting on a higher level/with very good gear/powers or in one of the few safe-ish places, with the clashing fiends being closer to background noise this sounds like a bad time for the MC/party- more so than usual on the lower planes.
With the running and the screaming and the gruesome deaths.
*Pun not intended.