Animate Undead Swarm

Choose a pile of bones or corpses of Medium or Small creatures within range. Your spell imbues the targets with a mimicry of life, raising them as an undead swarm. Your Hit Point Max is reduced by 5 until the spell ends. Your body can only support Proficiency Bonus swarms being Raised at a time, and you the spell ends when you take a long rest.

Your body can only support, a number of swarms equal to your Proficiency Bonus at a time. The Swarms may be dismissed at any time as a free action, but the Max HP Reduction for each Swarm that is Raised remains until you finish a long rest.

You may change the Casting Time to 1 Action by spending one of your Hit Die.

You can use a bonus action to mentally command all swarms you made with this spell if they are within 120 feet of you, that you can see. If you issue no commands, the swarm takes the Dodge action.

Undead Swarm
Size: small/medium 
Armor Class: 14 (natural armor)
Hit Points: 20
Speed 30 ft.

STR 16 (+3)   DEX 11 (+0)   CON 16 (+3)
INT 4 (−3)   WIS 14 (+2)   CHA 5 (−3)

Senses Darkvision 60 ft
Challenge — Proficiency Bonus equals your PB
 
Swarm: The swarm can occupy another creature’s space and vice versa. The swarms space is difficult terrain. The swarm cannot make AOO. 
 
Actions
Grave rend. Melee Weapon Attack: your spell attack modifier to hit, reach 5 ft., one target. Hit: 2d4 + 3 necrotic damage, STR save or Grappled. (Deals half damage when Bloodied)

At Higher Levels.
Your Max HP is lower by another 5 for each spell level above 2nd.
Increase HP by 5, damage by 1d4, for each spell level above 2nd.
Size Increases one size at odd numbered spell levels.