The Dark Summoner has been trained to bring minions to his side by the most powerful of Necromancers and Liches of the land, being able to command his own personal army to both protect and attack. Controlling dark minions that do best in the darker planes and places of the world, the Dark Summoner must be careful of enemy paladins and clerics who may bring their holy powers upon them.
As the Dark Summoner you will want to make the most of your swarms of allies to bog down your opponents and keep yourself in safety away from the thick of combat, taking on this role and summoning such adept in evil creatures costs your very essence to do.

Dark Speaker

You can Telepathically Speak to all of your summoners and both you are your summons can understand each other. 

Zombie Summons

Starting at level 1, You begin to practice your dark arts with the most basic of summons. As an action you summon 2 Zombies from the ground at the cost of 1d4 Hit points, the Zombies burst forth anywhere within 10ft of you at initiative order 10.

You may use this feature a number of times equal to your proficiency modifier before needing a short or long rest. 

Max Zombies summoned at a time.

• Level 1 - 2
• Level 6 - 4
• Level 12 - 6
• Level 16 - 8
• Level 20 - 10

A Nightmare Steed

At level 6, You must sometimes flee from combat or get to an advantageous place in which to control your minions. You can Call forth A nightmare from the lower planes using one of your zombie summons as a sacrifice to do so.

You can use this feature twice before needing a Short or Long rest. Only One Nightmare may be summoned at a time.

Vampire Allies

Starting at level 14, You can bring forth from darkness 2 Vampire spawns under your thrall, it is not recommended to summon these allies in the day. As an Action You may at the cost of 1d20 hit points for the summon of 2 Vampire spawn as the life force used brings them to your side. 

The max Vampire Spawn you may have summoned depends on level, Each additional Vampire summoned Costs 1D10 hit points - 

• Level 14 - 2
• Level 17 - 3
• Level 20 - 4

You can use this feature a number of times equal to your Constitution Modifier before needing a Short or Long rest.

Sacrificial Power

At level 18, You can turn you latent power into a way to prolong your life, which further lets you summon more minions to your side. As a bonus action you may 6 sorcery points to heal 3d10 health.

Sacrifice Brings Death

At level 18, you may use the life force of your summons to help you bring death upon your enemies. By sacrificing 2 of your summoned Vampire Spawn, you can cast Finger Of Death as an action that does not count towards your spell slots.
You can use this feature a number of times equal to your  Constitution modifier +1, You regain the uses after a Short or Long rest.