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Attacks: Summoning undead minions, damage over time effects (curses, disease, etc), Dark-aspected magic
Utility: Fear, curses/debuffs, raising undead impediments, maybe a death-y travel power (swapping with minions, changing form, etc)
Healing/Survival: Life-draining/vampirism/blood magic, transferring debuffs, sacrificing minions, phylacteries/lichdom, bone/soul barriers, undeath (ie ghost form), "fake health" effects, resurrection
You'll note that most of the categories under "attacks" have significant overlap with the listed utility and healing/survival trees (ie a drain effect as their main attack, curses that both DoT and adjust vulnerability or output).