Shall synonym Old English

In Old English (spoken approximately 450-1150 CE), concepts similar to "shall" were expressed through forms of "sculan" (pronounced roughly "shoo-lan"), the ancestor of modern "shall." Sculan functioned as a modal auxiliary verb expressing obligation, necessity, or future intention—similar to shall's functions in later English. Other Old English expressions for obligation, necessity, or future action included forms of "willan" (ancestor of "will"), "motan" (expressing permission or necessity, ancestor of "must"/"mote"), and "magan" (expressing ability, ancestor of "may"/"might").

The question might actually be seeking Modern English synonyms for "shall" that maintain formal or old-fashioned tone. Modern equivalents of "shall" include "will" (future tense in most contexts), "must" (obligation or requirement), "ought to" (moral obligation), "should" (recommendation or expectation), "is to" (formal obligation: "you are to report tomorrow"), or "have to" (necessity). "Shall" itself persists mainly in formal, legal, or biblical language ("Thou shalt not..."), contracts ("The tenant shall pay..."), and British English for simple future with first person ("I shall go"). Understanding "shall" versus "will" historically matters for interpreting older texts but has largely collapsed in contemporary usage, where "will" dominates and "shall" sounds deliberately formal or archaic except in specific legal or ceremonial contexts.