|High-Level Series (H1 - H4)||
High-level AD&D modules, developed in part to support the BattleSystem miniature combat rules.
H1 Bloodstone Pass almost qualifies as a boxed set, as it comes with cardboard cutouts and two booklets. The BattleSystem rules are required to play. The cutouts consist of 12 sheets of buildings and 104 counters (12 zombies, 15 orcs, 29 human sword, 22 human spear, and 26 peasants). (Thanks to Dan Harshman for this info).
Modules H2 - H4 have optional BattleSystem scenarios, but that boxed set is not required.
Module H4's level code is 18 - 100, and it's not a typo. Several pages in the module are devoted to the problems and complexities of dealing with 100th level characters.
There are no distinguishable printings between modules.
Thanks to Pat Wilshire for the scan of H4 Throne of Bloodstone.
Since H1 and H4 are rather bulky, they are more easily damaged than their thinner brethren, and thus less often found in pristine condition. Also, coming at the twilight of 1st Edition D&D, the print run of all four was rather small. However, the market value of these modules far exceeds even those considerations (and we really don't know why).