na-adjective, noun
in another league; on a totally different level
Slang abbreviation of レベルが違う, used to say someone or something is far superior or in a different class. Common in casual speech and online.
あの選手はレベチだね。
That player is in another league, isn't he?
このラーメン、マジでレベチ。
This ramen is seriously on a whole other level.