Was wondering this myself.

For me on extinction I added nameless venom as a drop from Mantisses so that it's a still a small challenge as you can only get em from the desert cave. You could do something similar in ur ragnarok world by adding the nameless venom as a drop from one of the mobs in there.

Mind you, overriding the loot from a dino will cause it to only drop the loot you make it drop so it wont drop other loot anymore unless you specify it. So I reccomend picking a dino that drops irrelevant loot like arrows etc and not a alphha raptor or something.

I put the following line in the Game.ini file to override the mantis drops :

ConfigOverrideSupplyCrateItems=(SupplyCrateClassString="DinoDropInventoryComponent_Mantis_C",MinItemSets=1,MaxItemSets=1,NumItemSetsPower=1.0,bSetsRandomWithoutReplacement=true,ItemSets=((MinNumItems=1,MaxNumItems=5,NumItemsPower=1.0,SetWeight=0.10,bItemsRandomWithoutReplacement=true,ItemEntries=((EntryWeight=1.00,ItemClassStrings=("PrimalItemConsumable_NamelessVenom_C"),ItemsWeights=(1.0),MinQuantity=1.0,MaxQuantity=5.0,MinQuality=0.5,MaxQuality=0.5,bForceBlueprint=false,ChanceToBeBlueprintOverride=0.00)))))

You can generate your very own override strings on this german (english translated) website. They have multiple tools to generate game.ini code in the browser.

http://www.nipiro.de/ark_crates_beta_318.php

Just follow the steps to select a dino and then specify which loot it can drop, you can choose multiple item sets that can drop aswell as specify the weight of that drop which simulates dropchances