As I have the Necromancer pack I didn’t actually think of this but Blizzard posted a reminder that anyone can take the Diablo 3 Necromancer for a spin without owning the DLC.
If you have not taken the plunge with the Necromancer Pack but want to try the class, you can via the new Challenge Rifts that launched with patch 2.6.0. The Necromancer is now in the rotation. As they point out, “it will be a while before we feature another Necro build.”
Definitely worth a look while you have the chance and it may help you decide whether the class is worth the purchase.