"Lure the Unwary" isn't a standard Magic keyword or ability—it's not part of the official rules glossary, and there's no widely recognized card or mechanic by that exact name. It may be a custom card, a homebrew mechanic, a misremembered name, or flavor text rather than an actual rules term.
If you encountered this on a card, check the reminder text in parentheses, which always explains what a mechanic does. If it's similar to "Lure," that ability forces all creatures able to block the lured creature to do so, which is a powerful trick in Commander for forcing bad blocks, pushing trample damage, or wiping out a board when paired with deathtouch.
If you can share the exact card text or where you saw "Lure the Unwary," I can give you a precise, accurate explanation of how it works.