The Spirit Butterfly

Your patron is a spiritual being that takes the form of a small, winged creature, such as a moth, firefly, and most commonly a butterfly. Despite its small appearance upon manifesting itself, this creature, known as the Spirit Butterfly, is immensely powerful, possessing an innate connection to reality itself and the minds and bodies of all that inhabit it. Its exact nature beyond this is shrouded in mystery, however, with most believing it to lack any form of sapience or motives for its actions.

The Spirit Butterfly may appear to living beings in one of its myriad forms seemingly with no particular purpose, though it is not unheard of for power-hungry individuals to summon it themselves. In any case, those that encounter it can often form a bond of sorts with it, and in doing so gain access to a limited portion of its power. This power allows them to connect to, control, and endow strength to others, which they may do selflessly, or for their own nefarious purposes.

(Creator's Note: I made this subclass a little while ago for fun and figured I might as well share it, rather than just show it off to friends. At the moment, I'm happy with it, but of course, I'm aware it may not be perfect balance-wise. Oh, and if you get what this is referencing, good on you.)

Expanded Spell List

The Spirit Butterfly lets you choose from an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.

Spirit Butterfly Expanded Spells

Spell Level	Spells
1st	Command, Heroism
2nd	Detect Thoughts, Warding Bond
3rd	Clairvoyance, Haste
4th	Dominate Beast, Polymorph
5th	Dominate Person, Geas

Spiritual Link

Starting at level 1, you have telepathy to a range of 30 feet.

Additionally, whenever you charm a living creature, you become linked to them for the duration of the effect. You and a creature that you charm gain the ability to speak telepathically to each other from any distance, so long as both of you are on the same plane of existence, and you are able to see and hear through your creature's senses, simultaneously to your own. If you have multiple creatures charmed at the same time, you can send telepathic messages to all of them at once, but your charmed creatures cannot telepathically communicate with one another, and you can only use the senses of a single charmed creature at a time. Which charmed creature's senses you use can be changed with an action.

Overbearing Will

Starting at level 6, your innate psychic connection with living creatures allows you to control them all the better. When casting an enchantment spell that charms one or more targets, you may select a single target affected by the spell. That target is given disadvantage on saving throws related to the spell cast on them, including any saving throw made to resist its initial effects or to end its effects early. 

You can use this feature twice, and regain all uses at the end of a long rest. The number of uses increases to three times at 10th level, and four times at 14th level.

Empower

At 10th level, you gain the ability to magically empower other creatures. As a bonus action, you can release a spectral version of the Spirit Butterfly in one of its myriad forms to fly towards a creature within 60 feet of you. The spectral Spirit Butterfly makes physical contact with the targeted creature, then disappears, and the targeted creature gains two of the following effects of your choice for one minute, or until you choose to revoke them (no action required):

• Elemental Attunement: The target deals an additional 1d6 damage with all attacks, or to a single target of any spell they cast. The damage type is one of the following that you choose when you use this ability: fire, cold, lightning, poison, acid, radiant, or necrotic. The target also gains resistance to the chosen damage type
• Hardy: The target gains a +2 to their armor class.
• Traverser: The target gains a flying, swimming, climbing, or burrowing speed equal to their walking speed.
• Short-Range Jump: The target gains the ability to teleport up to 20 feet as a bonus action.
• Enhanced Vision: The target gains truesight up to 30 feet.
• Enhanced Luck: After the target rolls a die and sees the result, they can use a reaction to reroll the die. They must use the new roll.

Upon using this feature, you cannot use it again until you finish a long rest.

Transformative Catalyst

At level 14, your ability to enhance the forms of others grows ever stronger. Whenever you successfully charm a creature within 60 feet of you, you may choose to instantly use your Empower feature on them (no action required) without expending your use of the feature. If the charmed condition ends on said creature while it is Empowered, the feature's effects are immediately removed. 

In addition, when using a bonus action to expend your use of your Empower feature, you may select a number of creatures up to your Charisma modifier (minimum of 1), all of which may be Empowered independently of one another.