NHF – new heroes for Heroes V 3.1.

You can set the maximum and minimum drop rates, like the incorporeality of ghosts (where you are guaranteed to hit on the 4th attempt).

Not exactly. Ghosts have a 50% chance to miss. After two misses in a row, the third attack will always hit, and vice versa, after two hits in a row, the third attack will always miss. That is, 1 out of 3 times you are guaranteed to miss and guaranteed to hit.