School of Malconvokers

Malconvokers practice an old art, long lost and untold. They study the minds and processes of nefarious, wild and otherwordly creatures and twist them into pacts with themselves. There are no malconvokers who weren't lost to the practice, swallowed by the creatures they tried to control. What waits for a malconvoker is inevitable; just how far they can try to push it is the only question.

Reach into the void

Beginning when you select this school you struck a pathway to exchange thoughts with nefarious creatures or minds from beyond. As a bonus action you can exchange some of your ether (spell slot of any level) for the knowledge of any warlock or wizard spell at any level you have a slot for. This knowledge stays with you until you take a short or a long rest.

Foresight

At 2nd level, you choose a type of creatures (aberration, fiend, fey or undead) you've specialized in your research. You craft protections against these creatures to ensure your intentions are not ruined by their malevolent nature. You are resistant to any damage done by these creatures.

Nefarious Contract

At 6th level, you choose from the following spells regarding what type of creatures you have specialized in:

Summon Fey
Summon Lesser Demons
Summon Shadowspawn
Summon Undead

and add it to your spellbook if it is not there already. Shadowspawn summoned this way are considered aberrations.

Whenever you summon any creature via this spell, it has additional benefits:

• You choose one damage type. Creatures summoned are resistant to this damage type.

Beginning at 4th level, you can extend your contract beyond it's limits and whip your summons to infernal fury. As an bonus action, make a Deception check against the summoned creatures Insight (Wisdom). If you succeed, the summoned creatures take one weapon Attack immediately on your turn and the creatures get a +2 bonus on weapon damage rolls and 1 extra hit point per your Wizard Level for the rest of the spells duration. 
If you fail your deception, the creatures turn immediately hostile toward you and your allies. They still gain the benefits from your bargain.

Improved Summoning

Beginning at 10th level, you do not have to concentrate on summoning spells, but you can dismiss any number of creatures summoned by you with an Action. You can also cast any summon spell you know as a ritual (with 10 minutes of casting time).

Once you attain 10th level, whenever you use a summon  spell to summon one or more creatures to your service, you summon one extra creature of the same kind.

Legion

Starting at 14th level, you can use magic to bring legions of nefarious creatures under your control, even those called fort by others. As an action, you can choose one creature of the type you have chosen when choosing this subclass (aberration, fey, fiend or undead) that you can see within 60 feet of you. That creature must make a Charisma saving throw against your wizard spell save DC. If it succeeds, you can’t use this feature on it again. If it fails, it becomes friendly to you and obeys your commands until it's dispelled or dies.

Intelligent creatures are harder to control in this way. If the target has an Intelligence of 8 or higher, it has advantage on the saving throw. If it fails the saving throw and has an Intelligence of 12 or higher, it can repeat the saving throw at the end of every hour until it succeeds and breaks free.