The Lords of Civilization (Hinnom national, and limited quantity) should take the prize. Nasty buggers.
Mandehas (late-game Lanka summons... quantity unlimited) come to mind. Decent magic, high hitpoints, flight... and autocasting Darkness, which is /very/ nice if you've got a lot of demons (which you quite probably do if you've done that much Blood research and have the blood income to get Mandehas).
Crossbreeding is nice for the instant volume (quite the bulk summons); even chaff can be fairly nasty with large-scale buffs. One might laugh at at a few hundred chaff... but perhaps not so much if they're Army of Lead + Mass Flight.
Lower-end, frost/storm demons are nice for flying shooters.
Re: Good blood summoning spells?
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