Yes, I know, I already have over 20 mobs, but listen, they're very important to worldbuilding.

Moss Agate Lizard

I had a plan some time ago about a Lush Lizard mob for the Green Agate Jungle, but this one's the more refined version. Passive and moderate in size and resemble Monitors.

Spitfire Drone

When the new biomes are implemented, Spitfire Drones are like stronger versions of Lesser Spitfires and have a different shape. These will spawn in the Volcaniclands, and potentially replace the Lesser Spitfires that spawn there.

Shockshooter Drone

Like Spitfire Drones, these may replace Lesser Shockshooters in the Static Wastelands.

Opalite Construct

Small constructs made of Opalite: a manufactured gemstone that resembles Opals. This reflects on the Mookaite Mesa's increased Opal generation.

Mookaite Golem

These golems are like the Crystal and Agate Golems, but these will protect any mobs that are EntityGolem or Opalite Constructs. Passive until provoked.

Aquamaids

Mermaids/Mermen of Aquamarine (cliché, I know). These will spawn exclusively in Aquamarine trenches, and are neutral. Will attack when provoked and they call upon reinforcements.

Golden Sapper

Growth Sappers that are adapted to Gold Biomes. These are passive and may drop Gold Nuggets or Shimmering Geodes.

Golden Leydrak

Lagrahks that have adapted to the Golden surroundings. Passive, and may drop Gold Ingots when slain. These are also much faster than their regular counterparts.

Golden Golems

Agate Golems that have been overcome with Gold. They are passive and don't attack other mobs due to their new nature.

Wulfenite Wolf

Rare mobs that acts as mini-bosses. They may spawn in Golden biomes and hunt alone, usually attacking other Golden Mobs, and will engage with the player if seen. They are stronger than their Blue Howlite Wolf counterpart, and may even attack them. They also have a ranged attack.

Prism Beast

Primal Beasts that have their molten bodies harden into prismatic forms. They are still hostile, but they now have the advantage to attack with ranged light-based attacks.

Unusual Naga

Contorted Nagas reformed by the unusual nature of the Anomalous Goldstonelands. These are not aggressive, and may attack corrupted mobs.

Weirded Sapper

Corrupt Sappers that have consumed the Green Goldstone from the Anomalous Goldstonelands. Completely passive.

Eroded Skeleton

Archaic Warriors with their skeletal structure weathered from the Salt Dunes. Spawns in the Crystal Salt Dunes, and hostile to the player.

Greater Nomadic Lagrahk

Rare Nomadic Lagrahks that only spawn in the "variant" biomes. While Nomadic Lagrahks spawn in almost every biome, a Greater Nomadic Lagrahk only spawns in Static Wastelands, Volcaniclands, and Crystal Salt Dunes. They almost resemble Ancient Lagrahks and may attack them.

Zenith Beast

Rare species of Primal Beasts made from the Extreme Magma. These will scorch the land beneath them and shoot exploding fireballs. Indifferent to Primal Beasts, and much larger and contorted.

Azurite Phantom

Phantoms that are passive and may drop items that may repel Phantoms. May also be used to create the Alpha Animate Soul.

Gaia Wanderer

Rare mobs that spawn all over Gaia, though in "safe" biomes. They contains various trades for items, each with their own class. This will be useful if a certain biome cannot be found, but a Wanderer has a trade for an item from that biome. Their classes are determined by biome rarity.

Esermera

Quadruped mobs that reach high speeds and can be ridden. Taming them requires feeding them Geodes, and can be ridden normally, or saddling them and there is more control to them. They will not wander around aimlessly without a saddle.