Ravana’s fatal oversight was omitting humans from his invulnerability boon

Evidence

Ravana was the king of Lanka. He had ten heads. He had twenty arms. He had been granted by Brahma a boon that no god or demon could kill him. … He had forgotten to ask for protection against humans. He had thought humans were beneath his notice. — , A Year of World Stories, 6532

Categorization

• XREF: Connects to the Achilles-heel pattern across world epics — Siegfried’s leaf spot, the Balrog’s unguarded detail.