Necromancer (5e Feat)

Prerequisites: The ability to cast a necromancy spell
You have mastered the art of animating and controlling undead.

When you cast a spell that creates or asserts your control over undead, such as animate dead, you can create or assert control over one additional undead.
When you cast a spell that creates or asserts your control over undead, such as animate dead, you have control over those undead for double the normal duration.
You can learn one additional spell of 1st level or higher from the necromancy school, if it is available to a spellcasting class in which you have at least one level, and it is of a level at which you can cast spells.