If you play a unit from your discard pile with Necromancy trait, you have to retuen it tothe bottom of your deck at the end of your turn.
if you play Warpstone Experiments on that unit, you have to sacrifice it at the end of your turn.

My question is at the end of your turn do you place it on the bottom of the deck or sacrifice it and place back in the discard pile?

Ok, so I found the Rules Summary, which answers questions 2 and 3...

I've just started a Dark Elf deck, and have a couple of questions;

1. If I trigger the Action on Lash the Prisoner and sacrifice the unit, do I get to put a resource put on Slave Pen? I'm assuming not, because the Slave Pen sacrifice is a triggered action itself, but wanted to check I was playing it right.

2. If I play Seasoned Corsair and target a unit with 2 hit points (reducing it to 0), is that unit immediatly removed from play? I'm not sure how the mechanic for HP reduction works.

3. Har Ganeth. Does the "less than 2 hit points" mean a unit's remaining hit points? As in, if a unit has 3 hit points and has taken 2 damage, can I remove it? Or does it just mean units with a printed HP of less than 2?
Also if a unit has 2 HP and I have Vile Sorceress, reducing a unit to 1 HP, is that unit removed from play then?

Thanks for the help.