The Abyssal Entropist is a wizard, who can gains powerful boons through their Abyssal Artifact. Activating one of these boons does come at a price. 

Natus Tenebrae

At 2nd,  level you may choose an appearance for your relic. It can range from a shard of a dark crystal, an amulet to a replaced abyssal bodypart.

So now choose the boon your abyssal relic grants you:

• Nocturnal Spellbinder - As a reaction, when a creature up to 30ft away from you casts a spell, you can sap energy from it, increasing the DC of the next spell you cast by the level of the spell you sapped the energy from.
• Black Rupture - When one of your spells damage a creature, you can have it take 1d4xYourWizardLevel Force damage as dark energy ruptures out of the creature. (up to 8d4)
• Shield of Night - As a bonus action, you can gain 1d4xYourWizardLevel temporary hitpoints until your next turn.
• Visions from the Void - A creature up to 30ft away from you gains disadvantage on any roll against you for 1 minute. It can make a DC(8+Your profficiency Bonus + Your intelligence modifier) Wisdom saving throw at the end of its turn to end the effect prematurely.

Then choose the price you have to pay to activate your boon:

• Blood - Sacrifice Max 2d4hp. The amount of dice increses by 2d4 after every activation of your boon. This resets on a short rest and you regain the lost HP on a long rest.
• Mind - Loose 1d4 Intelligence. The lost intelligence regenerates after a long rest.
• Fate - The next roll you make is made with disadvantage. You can only activate your boon again after making a roll.
• Memory - Forget a prepared spell.

Black Rupture

When one of your spells damage a creature, you can have it take 1d4xYourWizardLevel Force damage as dark energy ruptures out of the creature. (up to 8d4)

Blood

Sacrifice Max 2d4hp. The amount of dice increses by 2d4 after every activation of your boon. This resets on a short rest and you regain the lost HP on a long rest.

Fate

The next roll you make is made with disadvantage. You can only activate your boon again after making a roll.

Memory

Forget a prepared spell.

Mind

 Loose 1d4 Intelligence. The lost intelligence regenerates after a long rest.

Nocturnal Spellbinder

As a reaction, when a creature up to 30ft away from you casts a spell, you can sap energy from it, increasing the DC of the next spell you cast by the level of the spell you sapped the energy from.

Shield of Night

As a bonus action, you can gain 1d4 x WizardLevel temporary hitpoints until your next turn.

Visions from the Void

A creature up to 30ft away from you gains disadvantage on any roll against you for 1 minute. It can make a DC(8+Your profficiency Bonus + Your intelligence modifier) Wisdom saving throw at the end of its turn to end the effect prematurely.

Confortatus

At 6th lvl, you can enhance one of your spells through a 10 min ritual with your artifact. Choose a positive effect of the enhancement that will effect your chosen spell, that can be changed on level up:

• Ares - You may reroll 2 dice from the spells damage and must use the new rolls.
• Dionysus - When casting the spell, gain temporary hitpoints equal to its level. 
• Zeus - When casting the spell, choose a creature up to 30ft away from you, it takes 1d8 Necrotic and 1d8 lightning damage if it fails a DEX saving throw with a DC equal to your spell DC, as dark lightning strikes it.
• Poseidon - You can push up to 2 creatures affected by your spell up to 10ft in any direction you choose.  
• Artemis - The range OR radius OR width of your spell is increased by 5ft. For this to take effect either one of these values must be atleast 5ft.
• Orpheus - Your spell doesnt require V,S or M components and is invisible to anyone but you and creatures affected by it. True sight ignores this invisibility.

But casting the spell also poses a challenge. Choose a negative effect of the enhancement that can be changed on level up:

• Apicem - You cant cast the spell at a higher level.
• Luna - You can only cast the spell at night.
• Sol - You can only cast the spell at day.
• Immoderata - When you cast this spell roll a d4 on a 1 the spell takes affect on a target chosen by the DM.

 

Apicem

You cant cast the spell at a higher level.

Ares

You may reroll 2 dice from the spells damage and must use the new rolls.

Artemis

The range OR radius OR width of your spell is increased by 5ft. For this to take effect either one of these values must be atleast 5ft.

Dionysus

 When casting the spell, gain temporary hitpoints equal to its level. 

Immoderata

When you cast this spell roll a d4 on a 1 the spell takes affect on a target chosen by the DM.

Luna

You can only cast the spell at night.

Orpheus

Your spell doesnt require V,S or M components and is invisible to anyone but you and creatures affected by it. True sight ignores this invisibility.

Poseidon

You can push up to 2 creatures affected by your spell up to 10ft in any direction you choose.

Sol

You can only cast the spell at day.

Zeus

When casting the spell, choose a creature up to 30ft away from you, it takes 1d8 Necrotic and 1d8 lightning damage if it fails a DEX saving throw with a DC equal to your spell DC, as dark lightning strikes it.

Aurora Fracture

As an action, you may unleash a storm of necrotic and radiant energy centered on yourself by using yourself as a catalyst for your artifacts power. The storm is a sphere with a 25ft Radius and deals 6d6 Necrotic and 6d6 Radiant damage to anyone caught in it if they fail a WIS saving throw. Otherwise they only take 1/2 of the damage. You fail the saving throw automatically, but the storm will not drop you below 1 hitpoint. You may use this feature once and regain the use of it on a long rest.

Suscitans

You may cast spells with a casting of 1 action as a bonus action and increase its DC by 1d4+1. However if you do so this comes at a cost you will take 1d6 necrotic damage that cannot be negated whenever you cast a spell of 2rd lvl and higher adding 1d6 per spell level.