Q: After I search the top 5 cards. Do I shuffle any cards did not choose back into my deck?
A: Yes. Anytime you "Search", you always shuffle. -(Developer Ruling)
Q: What happens when I reveal Shadow of the Past and my nemesis minion has the same title as an enemy in play?
A: Your nemesis minion cannot enter the game in this instance, so it will remain set-aside and does not enter the game. However, you still reveal your nemesis' side scheme and shuffle the rest of your nemesis's set into the encounter deck. This will cause Shadow of the Past to gain surge as dictated by the card. -(Official FAQ)
Q: Can I target the villain with Shield Toss if I am engaged with a minion that has Guard and defeat it using the same Shield Toss?
A: You cannot target the villain with Shield Toss if you are engaged with a Guard minion because the damage is dealt simultaneously. Melee works different because it is split into two effects that each deal 3 damage. -(Developer Ruling, Hall of Heroes)
Q: Can you use Ms. Marvel's Shrink to increase the threat removed beyond 5?
A: Shrink modifies the amount of threat “that event removes” so the maximum of 5 applies. -(Developer Ruling, Hall of Heroes)