Colorado-based underground metal label Dark Descent Records had a hell of a year in 2014. Label owner Matt Calvert's consummate taste for all things twisted and grotesque spawned forth a number of fantastic albums from exciting extreme artists, with the likes of Thantifaxath, Emptiness, Swallowed, Lvcifyre and Horrendous making sizeable waves with their music and reaping plenty of critical acclaim in the process. Judging by early listening sessions to forthcoming albums by Ghoulgotha and Crypt Sermon, and the anticipation around the release of Finnish funeral doom titans Tyranny's long-awaited second album, it looks like 2015 will be another successful year for the label. This impression is given further weight once The Heart Of The Netherworld, the third full-length disc from Finland's Desolate Shrine, is experienced in full over numerous spins.

Spanning 60 minutes of atmospherically rich death metal sourced from the sacrosanct well of the old school while remaining focused on the future, The Heart of the Netherworld is a draining experience but also a rewarding one. The music of Desolate Shrine is masterminded by multi-instrumentalist LL, with deep lung-burning roars and higher pitched, yet no less impactful shrieks courtesy of two vocalists – RS (he of Dark Descent's Lie in Ruins) and ML. LL handles guitars, bass and drums as well as being responsible for recording, mixing and creating the band's evocative artwork. With two well-received albums behind him – 2011's Tenebrous Towers and their 2012 Dark Descent debut The Sanctum Of Human Darkness – LL has really grown into a strong composer in his own right, and his band's latest studio effort highlights his constant development.

Aided by a robust production job (a refinement that doesn't dispense with the cloaked, cloying aura previously heard on Desolate Shrine recordings), LL's conscientious approach to creating dynamic extreme metal by focusing on clever tempo changes has never been as apparent as it is now. After the ubiquitous instrumental opener – plainly titled 'Intro' – gives way to 'Black Fires Of Gods', the use of strident blasting sections backed by gnarled Swedish death metal-inspired guitars are offset by pounding half-time grooves and heart-racing double bass progressions. The bass-heavy, rhythmically circuitous transitions are smooth and shrewdly timed, thus the momentum is balanced even when a subtle, eerie melody is introduced before the song ends. It's this kind of fluid songwriting which continues to hold the listener's attention through the three lengthy tracks that comprise the majority of the album's run-time – 'Desolate Shrine', 'We Dawn Anew' and the title track.

The eponymous 'Desolate Shrine', for example, unfurls across nearly ten minutes and is founded upon the unease akin to Funeral Mist's malevolent and dramatic black metal (especially vocally); though its heavier sections are death metal to the charred bone. Blast beats are intermittent and not used as a crutch, and although some of the riffs are interchangeable at times, the variations in tempo and the dual vocals distract from this fact. From its Carpenter-esque tip-toe of horror piano, the 14-minute 'We Dawn Anew' beats the impressive construct of the title track to best encapsulate LL's development as a songwriter since Desolate Shrine's formation in 2010. The gothic sorrow at the heart of fellow countrymen Skepticism and Thergothon is found in the funereal doom tenets of this song's early movements; the bass lines being an essential counterpoint. Here, Desolate Shrine scale back the queasy attack favoured during 'Death' and the lock-step grooves of this album's most forceful and direct song, 'Leviathan'. By using disquiet as a dynamic, the scalding riffs and dual screams hit harder as a result – it's a time-tested trait more extreme bands need to learn how to incorporate into their music without favouring atmosphere over aggression; there's plenty of space for both, as Desolate Shrine prove time and time again during The Heart Of The Netherworld.

Albums of this length that channel close stylistic expression across each dense song are undoubtedly demanding; but like 70s prog rock, fans of underground metal are willing to invest time to engage with an artist's vision (they're also more inclined to call bullshit if the music isn't up to scratch). Desolate Shrine's vision is clear on their latest effort: create a uniform piece of music from start to finish which tests the listener but engages through some deft, non-linear songwriting to reveal many idiosyncrasies (the sparse incorporation of piano and acoustic guitars sound understated and complimentary and this aspect of the band's instrumentation may be further expanded upon in the future) the more time is spent immersed within. Because of its meticulous execution, there is no doubt that The Heart of the Netherworld is the most varied album of the Finnish band's existence. Consequentially, it's also their best album to date – not to mention a worthy addition to Dark Descent's much-admired roster of underground releases.