kev, does assassin damage or discard happen first? In other words if the assassin is killing our only Aether Pillar can I discard it first from our Aether duo deck that lost this round, thereby breaking the system?
No. Do the assassin damage first and then discard. Later in the Event when you discard 30 from your 30-card deck, if an assassin damages a card that you are already forced to discard, select one card from your vault instead.
This also applies for event cards?
Treat vault damage from CL exactly as Assassin damage, except you may be using a different column.
Also, say that assassins a card that i have 0 of after being forced to discard it. But! i can salvage it. Do i have to salvage it/discard it if i salvage it?
No. The assassination can be separate. If assassination forces you to discard your only Aether Pillar but you were discarding anyway you might select your last Aether Pendulum instead, for instance. If you also have an opportunity to salvage an Aether Pillar and/or an Aether Pendulum you may do so without impacting the assassination decision.