This is the only valuable ability. Seriously. The only one for the entire class. Compare this to other classes - they have about 3 working sets and a valuable lod. Which is actually still crappy cuz they must have 5 each. And some sets even have variations with different weapons (Akkan, Inna, Sunwuko). But necro can ONLY play corpse explosion. Are Bliz even even serious? It’s a paid character!
What I advice is bringing more thematics to the sets.
Trag Oul must use several blood spells.
Rathma must incude more stuff about bones.
Others may be cold themed, pet themed, thorns themed.
Lod also may have a variation to play with golem, skeletons and riviving enemies - because this will make it look like necro from D2.