Colossus

Armorer Artificer option

Extra Attack

Starting at 5th level, you can attack twice, rather than once, whenever you take the Attack action on your turn.

Colossal Modifications

At 9th level, you learn how to use your artificer infusions to specially modify your Arcane Armor. That armor now counts as separate items for the purposes of your Infuse Items feature: armor (the chest piece), boots, helmet, and the armor's special weapon. Each of those items can bear one of your infusions, and the infusions transfer over if you change your armor's model with the Armor Model feature. In addition, the maximum number of items you can infuse at once increases by 2, but those extra items must be part of your Arcane Armor.

Perfected Colossus

When you create your armor, you may have it be Huge instead of Large. While wearing your armor, you have advantage on Strength checks, and attacks you make with your Integrated Weapons have an additional 5 ft. of reach. 

Tools of the Trade

When you adopt this specialization at 3rd level, you gain proficiency with heavy armor. You also gain proficiency with smith's tools. If you already have this tool proficiency, you gain proficiency with one other type of artisan's tools of your choice.

Colossus

Colossal Armaments: The armor comes with integrated weapons which can be called to the armor's hands (as if drawing a weapon) whilst it is being worn. Each of these weapons count as a simple melee weapon with the reach property, and is deals 2d6 damage on a hit. The damage type of these weapons is the same as the most recent damaging spell you cast. If the spell had multiple damage types, you pick one. If you have not casted a damaging spell, the weapons' damage type is fire. These integrated weapons cannot be removed from the armor.

Gigantism: While wearing this armor, your size is large. You may use your Intelligence score, rather than Strength, when making an ability check that would normally require Strength. 

Armored Bulwark: The armor has thickened plating which protects the wearer from damage. The plating has hit points equal to 3 times your Artificer level. Whenever you take damage, the plating takes the damage instead. If the damage reduces the plating to 0, you take any remaining damage and the plating can't absorb any more damage until you take a long rest. The plating regains all hit points after a long rest.