It's easier for everyone if you link the cards
[mwcard=FWC08]Invisible Stalker[/mwcard]
When stalker attacks, he is visible until the end of the round, meaning in upkeep he will be invisible.
[mwcard=PSJ06]Pillar of Righteous Fury[/mwcard]
Pillar attacks are ranged 0-0 attacks. SIngle target attacks require targeting unless specified otherwise. Meaning pillar can not attack an invisible Invisible Stalker.