invincible, unstoppable, etc only last until something proves otherwise. juggy's the classic case to use - is he unstoppable? to 99% of things out there, yeah. there just happen to be characters who can literally rip a planet in half if they felt like it and are able to stop him. even if they didn't exist, he would only be as good as he's shown. doesn't really exist all in all. so no, saying something is invincible doesn't actually say anything, but infers a lot of things (e.g., if there were a series where a nuke is the highest level of damage possible, and something doesn't even get phased by it, in that series you can call it 'invincible,' however it's entirely worthless with higher level beings).
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The future must protect the clone's past.
"Maybe it's a tentacle, molesting the planet itself. - Aschen Brodel.