Some of my experiences with the spells:
Skeletons: There's no police better than them.
Ghouls: I probably under-utilized them, but they were competing with Shadow Demons.
Weakness: Surprisingly effective in early game.
Black Sleep: The first of many resistance based nukes. Pretty good at this point.
Night Stalker: Competing with Shadow Demons.
Wall of Darkness: Amazing. Casting it in battle saved me a couple of times.
Reaper Slash: Made me aware of how many creatures there are with Poison Immunity. Good when you get it, takes a backseat later on. Fine for an uncommon.
Lycanthropy: Only tested this once as an experiment. Pretty good in theory, just not that many opportunities in practice.
Drain Power: Tried it, a lot, but attempting to drain the AI to the point of it having effect seems futile.
Black Prayer: Death is shackled to this spell. Only once you have masses of Death Knights or Demon Lords can you consider not casting it, and even then you probably want to.
Shadow Demons: Great in early game, near useless in late (very slow). That's fine.
Blood Lust: Didn't see a use for it, though may be better with different picks.
Wraiths: Never cast one, though I think they're great. Death Knights just aren't that much farther away and do the same but better.
Wrack: Not very good in practice. Kills weak units, slowly. Funny in Benny Hill battles, especially with Terror. I do think it suits the Death theme well.
Warp Node: As I consider all nodes being for future-me, I didn't use it. But it may suffer from the same as Drain Power.
Famine, Evil Presence, Pestilence: Very devastating trio. AI rarely removes them.
Wave of Despair: Problem is, does little when you need it the most, but still useful on occasion. Strange how an exception is made for this spell to ALSO target resistance. Not like Death has a lack of them.
Massacre: Actually not that great. At this point, anything that dies by it isn't much of a threat anyway.
Final Wave: Same.
Annihilate: I'd hate to say this, but same.
Animate Dead: Really good.
Summon Demon: Actually don't like the chance between two different ones. Rather just always have the caster one. The fighter one isn't all that strong anyway.
Death Knight, Demon Lord: Without these, Death doesn't stand a chance. Doombolts actually kill the things you'd like the other spells to kill, and I'd trade any of them for it.
In summary... I don't know. I think Death has a couple must-have spells, many flavour ones, and a lot of resistance based nukes that are very good at killing stuff you don't really care about. That's probably great in combination with Zombie Mastery, but hordes of zombies don't have a lot of use themselves (they are slow, and limited by only 9 per battle), aside from garrisons/node guards. I quite like the idea of Death having more spells like Weakness - focusing more on strong disabling/debilitating effects in a (near) guaranteed way, and a bit less on hit-or-miss nukes.
Skeletons: There's no police better than them.
Ghouls: I probably under-utilized them, but they were competing with Shadow Demons.
Weakness: Surprisingly effective in early game.
Black Sleep: The first of many resistance based nukes. Pretty good at this point.
Night Stalker: Competing with Shadow Demons.
Wall of Darkness: Amazing. Casting it in battle saved me a couple of times.
Reaper Slash: Made me aware of how many creatures there are with Poison Immunity. Good when you get it, takes a backseat later on. Fine for an uncommon.
Lycanthropy: Only tested this once as an experiment. Pretty good in theory, just not that many opportunities in practice.
Drain Power: Tried it, a lot, but attempting to drain the AI to the point of it having effect seems futile.
Black Prayer: Death is shackled to this spell. Only once you have masses of Death Knights or Demon Lords can you consider not casting it, and even then you probably want to.
Shadow Demons: Great in early game, near useless in late (very slow). That's fine.
Blood Lust: Didn't see a use for it, though may be better with different picks.
Wraiths: Never cast one, though I think they're great. Death Knights just aren't that much farther away and do the same but better.
Wrack: Not very good in practice. Kills weak units, slowly. Funny in Benny Hill battles, especially with Terror. I do think it suits the Death theme well.
Warp Node: As I consider all nodes being for future-me, I didn't use it. But it may suffer from the same as Drain Power.
Famine, Evil Presence, Pestilence: Very devastating trio. AI rarely removes them.
Wave of Despair: Problem is, does little when you need it the most, but still useful on occasion. Strange how an exception is made for this spell to ALSO target resistance. Not like Death has a lack of them.
Massacre: Actually not that great. At this point, anything that dies by it isn't much of a threat anyway.
Final Wave: Same.
Annihilate: I'd hate to say this, but same.
Animate Dead: Really good.
Summon Demon: Actually don't like the chance between two different ones. Rather just always have the caster one. The fighter one isn't all that strong anyway.
Death Knight, Demon Lord: Without these, Death doesn't stand a chance. Doombolts actually kill the things you'd like the other spells to kill, and I'd trade any of them for it.
In summary... I don't know. I think Death has a couple must-have spells, many flavour ones, and a lot of resistance based nukes that are very good at killing stuff you don't really care about. That's probably great in combination with Zombie Mastery, but hordes of zombies don't have a lot of use themselves (they are slow, and limited by only 9 per battle), aside from garrisons/node guards. I quite like the idea of Death having more spells like Weakness - focusing more on strong disabling/debilitating effects in a (near) guaranteed way, and a bit less on hit-or-miss nukes.