Please add a biome blacklist to the config to make it possible to prevent the ores from occuring in certain biomes completely.

Version 1.8 on CurseForge now features a biome blacklist and whitelist. It uses BiomeDictionary types rather than Biome IDs to make it more compatible, so for your uses you just need to add DESERT, BEACH, and whatever type Defiled Lands uses for its biomes to the blacklist.

Hmm, I can look into this. Are there any specific Biomes that are causing issues?

No real issues. I want to blacklist deserts, beaches and the biomes from the Defiled Lands mod for aesthetic reasons.