Finland's foremost avant-rock jesters collide with hypnotic results on Circle and Pharaoh Overlord

You've to hand it to Circle. After nearly quarter of a century in the more mischievous end of the avant-rock business (2016 will mark the band's 25th anniversary), it's still virtually impossible to predict what a new Circle album will sound like.

However, you could safely bet a bundle on assuming it will be worth hearing. This despite the fact that the band and various offshoots (most notably bassist and Ektro label boss Jussi Lehtisalo's stoner rock monsters Pharaoh Overlord, singer and keyboardist Mika Rättö's hazily expansive balladeers Kuusumun Profeetta and guitarist Janne Westerlund's Plain Ride, whose Skeleton Kites was one of 2014's slept-on high points) churn out new produce at a rate that must make the extended Circle family one of the predominant small industries in their hometown Pori on the Western coast of Finland. Whether they're dabbling in muscular space rock dynamics (2010's superb Rautatie), a Kraut-infused gonzo takes on Metal (2005's Tulikoira) or ambient noodlin' (2006's Miljard), however, the outcome is always unmistakably the work of Circle. You couldn't possibly mistake their singular mixture of a zany hunger for the absurd and an uncompromising zeal for thoroughly serious musical exploration for anyone else. Recent UK dates saw the band, now expanded to a six-piece with guitarist brothers Julius and Pekka Jääskeläinen, sport outrageous amounts of lurid spandex and theatrical tomfoolery whilst whipping out turbo-charged displays of proggily sprawling yet dynamic and intense, resolutely cosmic hard rock.

These days, it's not enough for Circle to confound audience expectations with the music; the actual identity of, or "brand" Circle is also subject to some serious messing around with. A while ago, Circle rented out their name to a grunting Black Metal band whilst they - reborn as Falcon - delivered an album of cheddar-coated AOR. With these confusingly named albums, Circle and Pharaoh Overlord have seemingly become virtually one entity. With Rättö's inimitable high-and-loud wail largely absent on the mainly instrumental Pharaoh Overlord, the two bands borrowing each other's tricks and nearly identical line-ups, it's tricky to tell where Circle end and Pharaoh Overlord begin.

The baffling shifts in strategy elevate the music. The current Circle line-up has evolved into a fearsome unit capable of conjuring pure gold from the most spartan of ingredients, which pretty much summarises the plot for these albums. Circle especially is little short of revelatory. Shedding Pharaoh Overlord's customary riff worship, these sleek and spacious instrumental explorations sail towards the core of kosmische bliss on a choppy sea of analogue synths. The nearest equivalent to the retro-futuristic, repetitive hypnosis on offer here in the extended Circle catalogue would probably be Rättö & Lehtisalo duo's 2003 space truckin' classic "Valonnopeus." There's certainly no shortage of acts kneeling at the altar of Neu! et al. As unadorned, distinctly Michael Rother-ian guitar melodies and bubbling keyboard melodies float ever more weightlessly upwards whilst Lehtisalo's subtly dub-wise bass minimalism and drummer Tomi Leppänen's human metronomics maintain order at the control station on the likes of "Vilaa", there's plenty of unmapped territory left in this corner of the cosmos yet.

Comprised of five lengthy cuts of creepy-crawling unease, Pharaoh Overlord is a more unsettling beast. Despite being closer to the skronk side of Circle essayed most recently on Infektio (2011) than the band's more conventional offerings, the slow-burning slither of the densely layered and percussive material proves more immediately and richly rewarding than the last few Circle (or Falcon?) albums of 'normal' songs. The stern horn toots of guest Juho Viljanen and Rättö's wordless crooning add plenty of melodic hooks to the sputtering cauldron of swamp-y, sweaty grooves and abstract guitar emissions, whilst the bloodcurdling screams that interrupt the reverential levitation of "Kävelen Luiden Päällä" ('I walk on bones') will help set right anyone who mistakes the record for undemanding background music. By contrast, the multi-layered harmonies - anchored by an elemental bass rumble - that power up the latter half of the epic opener "Koitto" are downright heavenly. Circle must now count amongst the foremost musical cults in circulation. As such it makes a warped kind of sense that their new album is so often reminiscent of listening in whilst hooded figures go about their ungodly business in some candle-lit, damp subterranean lair.