Keep in mind that the character you want to banish needs at least five Strength, so use Happy, Good-Natured or Scepter of Arendelle to give strength to the character you want to banish if necessary
The text itself isnt attributed to any character and it doesnt mention anything directly related to Magic
It's best to keep this Warlock safe
Yes, you will need to Station 12 Power worth of Creatures to turn this on, but if youre playing a Creature deck that will come naturally
At each of your upkeeps, you can exile cards from your opponent's library based on the number of mercenaries you control and play them until the end of turn
While its true theres restrictions on Nasty End, in a format where you have access to a legendary creature in your command zone, the condition to draw three isnt that hard to meet