The recipe drops works based on all guaranteed reward drop systems (like Treasures of Tokuno, the Legacy Dungeons, Doom, Blackthorn's etc...) You accumulate points based on the fame of the creatures you kill. Vampire bats & corpsers aren't going to provide a terribly large amount of those points. We are monitoring all artifact/recipe/armor set drops and will make changes as appropriate in the future.@Kyronix How much luck is enough to make the recipe/armor drop rate not feel like a grind?
I spent three hours this morning killing tigers (~200), corpsers (~125) and vampire bats (~75) on a tamer wearing 2,060 luck suit, I used a GD to kill everything. I received zero drops.
I could have used a luck statue for an additional 950 luck, but since the effect only lasts an hour, its somewhat pointless.
The Dragon Turtle spawn isn't any better... in 12 runs (netting 4 eggs and 3 books) I've only received 1 recipe scroll (granted that's on a sampire with only 140 luck).