This addon adds 5 new variants to most mobs in Minecraft which spawn naturally. These tiers are wood, stone, iron, diamond, and emerald. Hostile mobs get more health depending on their tier and many mobs have new spawning locations to make your world more difficult.
You can find anything from wooden zombies to emerald evokers in your Minecraft world, each of them with their vanilla mob drops. This addon was intended to make your Minecraft world more difficult and interesting. Most higher tier hostile mobs are more powerful than normal ones.
All Tier Ravagers: