Netherite Sister Sets adds 3 new armor types.

Opal:

Opal is designed to be on equal standing with Netherite. It is more defensive, but lacks the higher durability, enchantability, and knockback resistance that Netherite Provides, resulting in a balance where one isn't necessarily better than the other, giving players the freedom to mix armor types for a personalized result.

Opal is found at y=45 and below, with an average vain distribution of 1 per chunk. Opal Ore produces a particle effect around itself, so if you see a particle floating in a cave, start excavating because Opal is nearby.

Opal can be upgraded from diamond in the Smiting table.

Enderium:

Enderium is a merroir set to Netherite, while Netherite is defensive by giving you knockback resistance, Enderium is on the offensive. Enderium Corodes away at the diamond it is mounted to, making it less defensive and have a lower attack, however, it reinvests that energy somewhere else. Putting on Enderium will cause you to gain the strength effect, building up from level 1 to 4 depending on how many parts of the set you are using, if you choose to use the less damaging tools of the set, they will inflict weakness on an entity you attack.

Enderium is found on the underside of End Islands (y=25 and below) and requires a Diamond Pickaxe to mine, finding it is easy, by flying underneath the islands, but harvesting it is significantly more difficult in most cases. If you succeed in such a challenge you will be rewarded with Enderium Pearls, combining the pearls with emerald in a crafting bench will get you Emerald Encrusted Enderium.

Applying Emerald Encrusted Enderium this to Diamond Armor and Tools in a Smiting table will give you the mysterious Enderium set.

Tin:

Tin is a stepping stone from stone to iron and aims to replace leather as the early game armor set (as leather will have a use to defend against the cold, preventing it from becoming obsolete). Tin is as defensive as leather, but more durable, the tools are right between stone and iron in almost every aspect.

Tin spawns at y=100 and below and can be harvested with a stone Pickaxe. Smelt the ore in a furnace to get a Tin Ingot.

Tin ingots can be used in normal Tool and Armor recipes to get it's respective output.

This Mod is in now way complete, feel free to leave creative criticism or ideas for new sets, it's my first mod so it's much appreciated.

Use this mod in any Modpack you'd like.