According to tooltips from the Occult Defence loot chests, a single wave completion ought to reward two glyph distillates, a signet distillate, and either a weapon or talisman distillate. And for completing three waves in succession, bonus Anima Shards, a glyph distillate, and an extra weapon or talisman distillate are to be rewarded. But, from data I’ve gathered and compiled in Onevia’s Occult Defence rewards thread, as well as from testimony from other players, it’s apparent that bonus rewards are not given for completing three waves in a row (though, it would seem it’s working somewhat for completing six or nine in a row). Completing a single wave actually rewards three glyph distillates, not two, as if the bonus glyph distillate for completing multiple successive waves is being doled out for less effort.
Moreover, since this system fails to reward bonuses properly–and because loot from a single wave starting with the 21st are identical, no matter if you complete one, two, or three waves together–players who are able to finish a single Wave 21 have little reason to continue with a scenario or attempt more difficult waves except for the challenge and the achievement. All the information we’re given within the game indicates we’re supposed to get better rewards the more success we have in completing waves, and yet this is not happening exactly as we’re informed.