Ryōmen Sukuna can only open the Furnace doors after first preparing his ingredients, Cleave and Dismantle.
Despite their absurd firepower, the flames within the Furnace lack both speed and range. To amend this, Sukuna undertook another Binding Vow.
"Outside of his Domain, Furnace cannot be used against multiple targets." This Binding Vow enabled Sukuna to not only reduce all within the Malevolent Shrine's range to dust, but ensure that all the resulting particles were matted in the explosive Cursed Energy akin to Furnace.
On top of this, Sukuna deftly altered the functionality of the Domain, to one that only allowed entry to living beings, maintaining the Shrines' output whilst sealing it airtight.
Thermobaric explosives and the transformed particle matter danced, raining down on every inch of the Domain.
The heat of Furnace spread the detonations immediately, birthing scalding, instantly compressing and decompressing shockwaves, ensuring the death of all living beings within the Domain. An attack capable of instantly obliterating Makora back in Shibuya. This is Ryōmen Sukuna's ultimate move.