I can't seem to find an answer to this question... and I made sure to check the Rules and Codex Supplement this time.
Does reanimating the Necromancer's "Eternal Servant" get a discount from [mwcard=DNQ02]Death Ring[/mwcard]? The Necromancer's reference card doesn't state that it counts as a "necro" or "undead" spell (probably because it isn't an action), but Reanimate is bolded and all other reanimation abilities are "necro" - and the creature being (re)summoned this way is "undead" by requirement of "Eternal Servant" ("you may pay mana equal to its casting cost to Reanimate it"). The Rules and Codex Supplement refers to the "Eternam Servant" getting "summoned" to the zone it was destroyed in, similar to [mwcard=DNE02]Rise Again[/mwcard] / [mwcard=DNI01]Animate Dead[/mwcard] and cards with the Reanimate keyword, but never calls this particular reanimation a "spell" as would seem to be required to get Death Ring's discount.
For example, I'd like to have an "Eternal Servant" [mwcard=DNC09]Plague Zombie[/mwcard] in a key combat zone, have him attack during his activation, then sacrifice him to an [mwcard=MW1J20]Altar[/mwcard] to trigger his ability upon being destroyed (and to give melee +2 and piercing +2 to a friendly), then reanimate him to do it all next turn. With the Death Ring, does it cost 9 or 8 to reanimate my "Eternal Servant" Plague Zombie? It seems to depend on his "casting cost". Is the casting cost always 9, as printed on the card, or is it 8 because I would get a discount if I casted it as a spell?