Hard scrambles use longer words, less common vocabulary, and scrambles engineered to preserve nothing of the original word — no leftover letter pairs, no anchored first letter. Expect eight- and nine-letter answers where brute-force reading fails and you have to work letter frequencies and word structure.
Repeated letters raise the difficulty further: a rack like O-T-C-A-L-E-H-O-C hides its doubles, and spotting them is half the solve. Hints reveal one locked letter at a time when you need a foothold.
Warm up on the daily puzzle first — then come back and see how many hard rounds you can clear without a hint.