Thou have an impossibly vast discography outside of their full lengths, and while generally at least solid, results still vary. Their trio of EPs leading up to Magus were wonderful explorations of different facets of their sound. Something like this, however enjoyable it may be when its on, doesn't have an abundance of replay value. This is a serviceable showcase of two sludge bands doing what they do, but it's a world away from Thou's more memorable work (for Haarp I can't really expound on where it fits into their overall discography, because this is the first time I've ever heard them).
Thou goes for the slow burn here, and it just doesn't pan out like it does on a lot of their stronger material. The wandering burnt-out wastelands vibe is really cool, but that's most of what the song has going for it. The riffs are incredibly slow (even by Thou standards), and I feel like they wouldn't amount to much of all if stripped of the massive simmering production. That isn't to "Black Steel in the Hour of Chaos" is a bad track, it just feels a bit style over substance. I don't remember any of the riffs and nothing sticks out to me about the songwriting once I turn it off.
Haarp gives us some burly sludge that skews hard towards hardcore. I'm not sure I'll come back to this (although I may check out one of their albums at some point), I did enjoy this more than Thou's side. They do a great job at twisting simple riffs and giving them an off-kilter feel. The riff that starts just after the first minute feels like blindly stumbling down a never-ending staircase. The brawny barks are powerful and the drummer sounds like he's having a lot of fun and definitely knows his way around a fill or two.
This is one of those side-discography things where it's fun to jam once, but I doubt I'd ever come back to. It seems like this Thou song was thrown in because it couldn't make the cut on their bigger releases. While not jaw-dropping or anything, Haarp was genuinely really interesting and I reckon I'll give one of their albums a go one of these days. You can skip this one, but it's serviceable enough to be decent while its on.