How to get creature knowledge to level D

Is there any way to encourage a creature to spawn, or to otherwise guarantee raising a creature’s knowledge to Rank D (so I can start Hunt missions to Rank C, so I can Divination Candle, so I can summon one)?

20+ runs in Cutthroat Jungle for a stupid Oculum Leech. Zero Oculum Leeches. Is there any way to solve this (aside from luck)?