Pact of the Arm-Cannon - a new Warlock option with four Eldritch Invocations

# Pact of the Arm-Cannon
One of your arms is a gift from your patron: a magical cannon that enhances your Eldritch Blast spell.  You may have lost the original arm in combat, or you may have deliberately removed it to accept this pact.  You must know the Eldritch Blast cantrip in order to select this pact.

### Arm-Cannon Benefits
Your Eldritch Blast spell deals d12s instead of d10s damage.  You don't roll at disadvantage when you target a creature within melee range with Eldritch Blast.

### Arm-Cannon Penalties
It's up to the DM to decide the penalties of having only one arm, although this author thinks imposing disadvantage on ability checks that normally require both arms is reasonable.
### Arm-Cannon Appearance
The appearance of your arm-cannon depends on your patron.  Here is how it might look.
##### Archfey 
Your arm-cannon is made of beautiful carved wood.  There may be small plants growing out of it.
##### Celestial
Your arm-cannon is smooth and made out of precious metals or marble.  It is engraved with glowing runes in Celestial.
##### Fiend
Arm-cannons given by fiendish patrons vary wildly in nature, but always match the of the specific patron.  For example, Dispater bestows iron arm-cannons (like the one seen at right) while Baphomet's cannons are composed of the horns of a great beast.
##### Great Old One
These arm-cannons can also take a multitude of shapes, such as a tentacle or a massive scroll displaying ever-changing and maddening text.
##### Hexblade
Hexblade arm-cannons are made of the angular, hardened essence of the Shadowfell.
##### Lurker in the Deep
Arm-cannons from benthic patrons range from crab-like pincers to sucker-covered tentacles and a column of pure elemental water held in place.
##### Raven Queen
The Raven Queen gives her champions arm-cannons made of onyx and covered with black feathers.

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##### Seeker
Seeker patrons gift unadorned, artificial limbs that come equipped with practical exploring devices like built-in compasses and telescopes.
##### Undying
Arm-cannons from these grim patrons are without fail made of undead flesh and bone.

### New Eldritch Invocations

#### Charged Blast
Prerequsite: 5th level, Pact of the Arm-Cannon feature

When you cast Eldritch Blast, instead of multiple beams, you can fire a single, empowered beam.  This single beam does the combined damage of all your Eldritch Blast beams.  This includes your Charisma modifier if you have the Agonizing Blast invocation, but does not include extra damage from spells like Hex or similar features like Hexblade's Curse.  For example, an 5th level warlock with Agonizing Blast and a Charisma of 18 casts Hex and then Eldritch Blast using Charged Blast.  If it hits, the target would take 2d12 base damage plus 8 because of Agonizing Blast and 1d6 more because of Hex.
#### Leaping Blast
Prerequsite: 9th level, Pact of the Arm-Cannon feature

As a bonus action immediately before attempting to jump, you can fire your arm-cannon into the ground to create a burst that propels you.  This triples the distance of the jump.
#### Rapid Blast
Prequisite: 13th level, Pact of the Arm-Cannon feature

You can cast Eldritch Blast as a bonus action once. You can't do so again until you finish a long rest.

#### Omni-Blast
Prerequsite: 15th level, Pact of the Arm-Cannon feature

When you cast Eldritch Blast, you can change the damage type to any type of damage.  You can select a different type of damage for each bolt.
######  Art Credit: Dave Kendall