The necromancer is a 7th-level spellcaster, thier spellcasting ability is Intelligence (spell save DC 13, +5 to hit with spell attacks). The necromancer has the following wizard spells prepared:  

Cantrips (at will)

1st-level (4 slots)

2nd-level (3 slots)

3rd-level (3 slots)

4th-level (1 slot)

Grim Harvest. Once per turn when a living creature fails a saving throw against or is harmed by one of the necromancer’s Necromancy spells of 1st level or higher, the necromancer regains hp equal to three times the spell’s level.   Undead Thralls. When the necromancer casts animate dead, it can target one additional corpse or pile of bones, creating another zombie or skeleton, as appropriate. Undead created by the necromancer have an additional 7 hp and a +2 to their weapon damage rolls.