What is the first jutsu used in the fight between orochimaru and sarutobi?

The first jutsu used in the fight between Orochimaru and Sarutobi Hiruzen is the "Reaper Death Seal" (Shiki Fujin). Sarutobi employs this forbidden technique to summon the Shinigami and seal away Orochimaru's soul. This jutsu highlights Sarutobi's determination to protect the village at the cost of his own life. The battle showcases the clash of their powerful abilities and the stakes involved.