Here is the full list of all 35 Nekro achievements.
Bestow the moniker of "Vance."
Beat the campain with the Alchemist Powerset.
Beat the campaign without eating any animals.
Beat the campaign without using any Trinkets.
Issue 500 orders to your summons.
Issue 250 orders to your summons.
Issue 150 orders to your summons.
Issue 50 orders to your summons.
Defeat Mayor Biscuit without dying.
Defeat the Citadel stage without dying.
Beat the campaign with the Outcast Powerset.
Beat the campaign without dying.
Use 10 different trinkets in one campaign.
Beat the campaign with the Grimm Keeper Powerset.
Beat the campaign without taking any Nekro upgrades...you dirty boy.
Kill 35 Hunters.
Summon 30 Punges.
Kill 35 Zealots.
Kill 35 Townie Elites.
Kill 35 Witches.
Issue 10 orders to your summons.
Summon 30 Darkseeds.
Kill 50 basic Townies.
Kill 10 Mushroomheads.
Kill 50 Lumbros.
Smack 50 enemies with the Grimm Keeper's skull bag.
Kill 30 Pigs.
Kill 30 chickens.
Summon 30 Horrors.
Deploy 100 scourge.
Throw 50 healing vials.
Pull 50 enemies with the Outcast's chain.
Do any description of anything.
Find and befriend the Giant Flaming Bear.
Kill 35 Priests.