Trying to pin down the best Urdu equivalents for 'invincible' is oddly satisfying to me — it's like matching a cosplay to the character down to the last stitch.
I’d put 'ناقابلِ شکست' (na-qabil-e-shikast) at the top of the list. It’s literal and commonly used in both formal writing and everyday speech to mean 'cannot be defeated.' Close behind is 'فتح ناپذیر' (fath-na-pazir), which carries a slightly grander, older feel — you find it in poetry and historical texts; it literally means 'not susceptible to conquest.'
If I want a colloquial punch, I reach for 'لاجواب' (lajawab) — it’s more like 'unmatched' or 'peerless' and feels lighter. For something that emphasizes unconquerability — especially of places or hearts — 'ناقابلِ تسخیر' (na-qabil-e-taskhir) works well. Lastly, 'غالب' (ghalib) is shorter and poetic, meaning 'prevailing' or 'victorious,' but it’s less absolute than 'ناقابلِ شکست.' I love how each choice shades the feeling differently; language is a small battlefield where words win or lose, and these feel like champions to me.