Oath of the Emerald Light

In forests deep where darkness dwells,
In dungeons dank beneath ancient fells,
Let those who seek to rule the night
Beware the power of the Emerald Light!

Expanded Spell List

You learn the following spell when you take this subclass. You know these spells and they are always prepared for you, and do not count against the total number of spells prepared.

Shield, Sanctuary
Levitate, Spiritual Weapon
Intellect Fortress, Protection From Energy
Resilient Sphere, Fabricate
Legend Lore, Bigby's Hand

Whenever you gain a level in this class, you can replace a spell from the expanded spell list with any spell from the cleric or wizard spell list. The spell must belong to the abjuration school of magic, or revert back to the original expanded spell list.

Channel Divinity

When you take the oath at level 3, you gain the two following channel divinity options:

Summon Weapon: As a bonus action you can summon forth a weapon made up of tangible radiance. You decide the type of weapon whenever you summon it. You are considered proficient with it, and you add your Charisma modifier to the attack and damage rolls of the weapon. The weapon deals 2d4 radiant damage. Should the weapon need ammunition, it creates it's own for every attack as it is made. You can use your Divine Smite feature, "Smite" spells and Improved Divine Smite with the weapon.

The weapon lasts for 1 hour, and can be dismissed and summoned again to your hand as an object interaction during this time. It is not dispel-able and is not subdued in an anti-magic field.

Once you reach level 11 in this class, the damage type can be changed to Force instead of Radiant whenever you use this Channel Divinity Option, as your constructs grow stronger. The damage die turns from 2d4 to 2d6.

Emerald Shield: As a reaction triggered by you or an ally being targetted by any harmful effect, spell or attack, you can use a charge of your Channel Divinity, you can negate that instance of damage or condition applied for yourself and a number of creatures within 30ft of you upto your proficiency bonus.

Aura of the Emerald Light

Starting at level 7, creatures of your choice in your aura gain a bonus to their Dexterity Saving throws equal to your proficiency bonus.
Creatures of your choice who start their turn or enter into your aura also gain a flying and swimming speed upto their movement speed and no longer need to breathe. This benefit lasts for 1 minute and can be renewed.

The Emerald Sanctuary

Starting at level 15, whenever you cast an abjuration spell, you can target a number of creatures upto your Charisma modifier to benefit from the spell for the same duration (minimum of one round, ie, start of their turn). You can use this feature a number of times your Charisma Modifier, and you regain all expended uses whenever you finish a long rest.

Holy Emerald's Might

Starting at level 20, once per long rest, you can unleash the true power of the Emerald Light within you. You build a mech around yourself as a bonus action, piloting it as part of the same bonus action. The stat block of the Mech is given here. You are considered mounted onto it and cannot be dismounted against your will. Its hit points are 20 + 25 times your charisma modifier, and AC is 15 + your Charisma Modifier. However, you can no longer concentrate on spells or other abilities requiring concentration.

Your mental ability scores replaces the mech's, its strength and constitution ability scores are replaced by your charisma score, and it adds its proficiency bonus to its skills and saves that you are proficient in. Your aura of protection now originates from the Mech instead of you. You can let the spells that target you also target your mech, and you can treat your mech as your self for triggers of any reactions. You can use your Divine Smite Feature through your mech and your Improved Divine Smite feature with the Slam attack.

In combat, you and the mech share the same turn, the same actions and reactions.
While in your mech form, creatures in your aura gain a bonus of d4 to their attack rolls and saving throws.

The Mech lasts for an hour, unless destroyed early. It is not dispel-able and is not subdued in an anti-magic field.
Once used, you cannot use it again until you finish a long rest, unless you expend a 5th level spell slot to use it again.