You have made a pact with a fallen god--a being still possessing great power, but only a dim reflection of the power it used to hold. Perhaps your patron was cast out of her pantheon by her fellow immortals, due either to jealousy over her power or anger over a betrayal. Or perhaps she lost a long campaign for power against another god, and the price was the loss of her divinity. Or maybe your patron has simply been forgotten, passed over by the march of time. His worshippers all met with an ancient cataclysm, and his power was diminished without followers to glorify his name.

Whatever the case, your patron is a shell of its former self. Previously immortal and thought to be unassailable, she has fallen from the heights of grace. Still long-lived, it may even be that she is now mortal, and will eventually completely fade away over the centuries. But whatever the case, your patron still has power now. And it has selected you to be its agent in the world, the recipient of a small portion of those precious reserves.

Your patron's motivations betray the hopelessness it feels. The forgotten, haggard, former god-king, sitting alone on a cracked throne under a crumbling mountain, sends you into the world to finally accomplish what it could not. Perhaps the defeat of another god, the ruin of the plans of his ancient enemy. Perhaps the recovery of his lost and fabled armor, or locating the body of his tragically slain wife. It may be that, due to its loss of her power, a minor member of a lost pantheon prefers to remain hidden, working what deeds she can in the shadows. Maybe the continued fight against the forces of chaos is all she wants from you. Or maybe, just maybe...you are to be an old deity's new prophet, the spark of a new flame of worship that will raise him back into glory.

Examples might be a god beloved millennia ago, but cast out by his father and siblings for his betrayal of his sister to an archfiend; or a deity who posed as a goddess of love, only to be revealed as a trickster, shapechanger, and assassin; or a mysterious entity who's name was stricken from creation when he challenged his older sibling for leadership of the gods. Whoever your patron, few alive today will recognize their name, and those who do may believe she is simply a myth, an old story and nothing more.

Your patron may exist on another plane--though not its plane of origin or power. Or it may even exist now only in a physical body, here on the material plane and as corporeal as the pitiful few agents it imbues with power.

The powers you are granted by your patron reflect your perhaps unique position--you are a scion, and in some ways also a priest, of this ancient power.

Fallen God Expanded Spells

The Fallen God 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.

 1st- Command, Guiding Bolt

2nd- Augury, Warding Bond

3rd- Bestow Curse, Glyph of Warding

4th- Divination, Guardian of Faith

5th- Geas, Hallow

Spite of the Fallen

Beginning at 1st level, if you are at less than full health, you have advantage on your first attack each turn against an opponent who hit you with an attack or spell on their last turn. 

Whispers of Ancient Might

Starting at 6th level, when you are hit by an attack, spell, or any effect causing fire, cold, lightning, force, necrotic, or radiant damage, or when you are hit by an attack from a celestial, fiend, undead, extraplanar being, or an attack drawing its power from such sources (DM's discretion--a clerical spell, an eldritch blast from a fiend pact warlock, etc.), you may call upon the power of your patron to grant you resistance to that damage type until the end of your next turn. You must choose to invoke this power before damage dice are rolled. You may also then choose to have advantage on your next attack, spell, or other effect directed at this attacker, or for their next attack, spell, or other effect to be at disadvantage.

Once you use this feature, you can't use it again until you finish a short or long rest.

Power of the Forgotten

Starting at 10th level, you can erase the memories of other beings, even removing all memory of yourself from the mind of another creature. 

When you use this feature, choose one of the following effects:

• On a failed Wisdom save, up to 10 creatures of your choice forget the events of the last minute.
• On a failed Wisdom save, 1 creature of your choice forgets the events of the last 10 minutes.
• On a failed Wisdom save, 1 creature of your choice forgets everything that they know about you. The creature retains its memories of everything else, but remembers nothing of who you are or that it has even seen you before. The affected being will unconsciously adjust other memories as needed to make its memories make sense--someone stole it's money pouch, but it doesn't know who. It was chasing someone down the street, but never saw their face, etc. 

These memory losses are permanent, although of course the affected creatures can come to form new memories going forward as usual.

Once you use this feature, you cannot use it again until you finish a short or long rest.

Rage of the Dying

Starting at 14th level, you can channel your patron's anger and fear of its mortality into an attack. One chosen enemy suffers the effects of dramatic aging. This feature effects even beings who do not normally age. If it fails a Wisdom save at disadvantage versus your Spell Save DC, it suffers all of the effects of a Slow spell for the next minute, and physically withers (-4 to strength and constitution saving throws). Additional Wisdom saves as per the Slow spell are at disadvantage. You do not need to concentrate to maintain these effects. At the end of 1 minute, the target reverts to its previous age and physical condition. If the target is a being that does not normally age or normally ages very slowly (DM's discretion--fiends, celestials, dragons, fey, etc.) it must make a second Wisdom save or suffer 3d6 Psychic damage from the experience. 

Once you use this feature, you cannot use it again until you finish a short or long rest.