Summon Undead

You call forth an Undead spirit. It manifests in an unoccupied space that you can see within range and uses the Undead Spirit stat block. When you cast the spell, choose the creature’s form: Ghostly, Putrid, or Skeletal. The spirit resembles an Undead creature with the chosen form, which determines certain details in its stat block. The creature disappears when it drops to 0 Hit Points or when the spell ends.

The creature is an ally to you and your allies. In combat, the creature shares your Initiative count, but it takes its turn immediately after yours. It obeys your verbal commands (no action required by you). If you don’t issue any, it takes the Dodge action and uses its movement to avoid danger.

Using a Higher-Level Spell Slot. Use the spell slot’s level for the spell’s level in the stat block.

In addition to the noted usage of the spell's level in the spirit's Traits and Actions, the following attributes are also affected.

Undead SpiritAC11 + the spell’s levelHP30 (Ghostly and Putrid only) or 20 (Skeletal only) + 10 for each spell level above 3Speed30 ft.; Fly 40 ft. (hover; Ghostly only)PBequals your Proficiency Bonus