School of the Dark Arts

In great libraries of archmages and magical universities, deep in basements, hidden by shelves, and sealed behind magical wards are the unspeakable arcana that any proper wizard knows are better off not being known. Blood magic and witchings and infernal translations are dangers that hold tantalizing knowledge for those wizards bold enough to wade into the darkness. Some of wizards of the School of Dark Arts look to master the most dangerous forces to serve as magical wardens. Others look into the shadows and see a truth that most are too frightened to accept and the power it offers. Too often, earnest wizards step forward as the well-intentioned former and find themselves become the terrifying latter, twisted by the knowledge they’ve unearthed.

Dark Art Savant

Beginning when you select this school at 2nd level, you learn one eldritch invocation. You may choose 1 cantrip and 1 first-level spell from the warlock spell list to add to your spellbook. This cantrip and spell are always prepared and don't count against the number of spells you can prepare. When you level up, you can choose to add 1 spell of a spell level you can cast from the Warlock spell list in place of a wizard spell. Intelligence is your spellcasting modifier for any Warlock spell or feature added this way

Warlock Cantrip

You can add a warlock cantrip and spell to your spell list

Unsealed Power

Beginning at 2nd level, you can harvest power from those you defeat in battle. When you kill a creature, you can harvest their soul to power your spells. You can exchange a soul to reduce the cost of copying a spell into your spellbook by 50g and 2 hours per soul. 

Unlike other wizards, you rely on the power of stolen souls rather than learning for your magic. You must expend souls for each spell slot beyond level 2 in addition to a spell slot to cast it. (e.g. a third level spell requires 1 soul, a fourth level spell requires 2 souls.) You may expend more the required souls per cast. If you do, the spell is cast at one level higher per additional soul expended. You cannot expend more than 2 souls this way.

When you take a long rest, you can only retain a number of souls equal to your proficiency modifier + intelligence modifier. All other souls are lost. If you have no souls, you suffer mental torment and cannot long rest. You also lose current hit points and maximum points equal to 1d10 for each level you have in Wizard.

Dark Knowledge

Your ability to harvest souls has improved. Now you may harvest souls of recently dead creatures whom you dealt damage to. You may also recapture 1 soul when you use Arcane Recovery. When you cast a spell, you can choose to instead expend twice the number of souls as the chosen spell slot level. If you do so, you cannot use Unsealed Power to empower the spell. 

Chained Souls

Your mastery over the control of souls under your thrall has improved. The number of souls you can retain under your control per long rest is uncapped. When you are reduced to
0 hit points, you lose control over all souls. You can regain 1 hit point per soul lost or hit points equal to your proficiency bonus + Intelligence modifier, whichever is less.

Dark Lord

Starting at 14th level, you have achieved supreme mastery over the dark arts. You gain the following enhancements to your spell casting:

• You may expend a number of souls up to the number of damage dice rolled. For each soul expended this way, a damage dice is considered to roll max damage. 
  
  
• You may expend a number of souls up to your proficiency bonus. For each soul expended this way, you may have the spell deal an additional 1d10 necrotic damage.