Scorching Inferno is a special move used by the legendary enemy, Nidhogg.
Nidhogg produces a ball of inferno in its mouth and releases it in a stream of flames that is extremely hot and powerful as it was able to deal major damage to a Duel Avatar in one hit.
Nidhogg used this move several times in his fight against Black Lotus and Crimson Kingbolt. Sulfur Pot has Nidhogg use this ability in conjuction with his Charcoal Smoke ability in order to ignite it setting anybody in the cloud of gunpowder on fire.