Sinker

You're a member of the Doomguard who's been in contact with the massive, sentient Iron Golem called Coaxmetal.  In exchange for your vow to spread entropy throughout the planes,  Coaxmetal has fashioned you an Iron Ingot Heart to ingest, a token that causes chaos and disorder to regard you as a companion.  Once activated, this ingot allows mutates the Sinker that has swallowed it, slowly transforming them into a living weapon, a hybrid of flesh and steel that spreads destruction in its wake.

Expanded Spell List

The Sinker 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.

Sinker Expanded Spells

Doom Knight

Your symbiotic pact with Coaxmetal has hardened you to the deterioration of the Multiverse, all the better to carry it out yourself.  You use your Charisma rather than Constitution modifier to calculate your hp.  This entropic symbiosis further expresses itself in the Doomguard's Eldritch Blast.  Between each short rest, a number of times equal to his proficiency bonus, the Doomguard may take a bonus action to cause their next Eldritch Blast attack to manifest as a piercing lance, flesh-ripping hail of razors, or virtually any other implement of war.  Mechanically, this changes the damage type of the blast from Force to Bashing, Slashing or Piercing.  If the Warlock can fire off multiple blasts in one round, a single bonus action may transform each ray into only one type of damage.

As a last laugh to existence, even dying affords the Sinker a chance to bring the end of everything just a little bit closer.  Each time the Doomguard rolls a death saving throw he emits a field of ruinous energy that deals 1d6+proficiency bonus necrotic damage to everyone within five feet, friend or foe.

Sifting

The Sinker picks up broken rubbish, charred wood, ground dust; etc, and lets the material filter through his fingers as he spends a round in quiet contemplation.  When they have finished their reverie they learn what caused the destruction. 

The Sinker rolls Charisma + their Proficiency bonus to determine how far in the past they may see.  If successful, the Sinker gains a psychic impression of what caused the destruction.  If the Sinker beats the DC by 5 or more they may expend a spell slot to bear witness to the past, present, or future of the destruction for a number of minutes equal to the spell slot expended.  A Sinker may use this ability a number of times equal to their proficiency bonus between each long rest.

DC

5  -  Up to one year in the past

10 - Up to ten years in the past

15 - Up to 100 years in the past

20 - Up to 500 years in the past

25 - Up to 1,000 years in the past.

Entropic Blow

At 6th level the Sinker embodies not just entropy on an abstract scale, but your end, this moment; right now, berk.  Between each long rest, a number of times equal to their proficiency bonus, a  Sinker may supercharge their attacks with any destructive force the planes have to offer.  As a bonus action, the next time you attempt to damage an opponent by spell or weapon, the attack type changes from its prior state to whatever damage type is preferred by the Doomguard, including elemental, radiant,  psychic, necrotic, or force.  If the enhanced attack misses the target, that use of Entropic Blow is wasted.

Nothing to see here

Not getting to level 10

Still nothing

Zilch