In a heroic manner; with the courage, nobility, or grandeur of a hero.
From heroical plus -ly (Old English -lice), the standard English suffix for forming adverbs from adjectives.
Heroicly is the archaic adverb form—modern English prefers 'heroically' with the extra 'a'—showing how English constantly adds letters to make pronunciation smoother.
Complete word intelligence in one call. Free tier — 50 lookups/day.