Once per turn, when you play a card that originally costs 5 or more, select an enemy leader or enemy follower on the field. Deal it 3 damage and draw a card.
QIf this follower is on my field, and I play Tomoe Murakami for 4 play points by discarding a card, will this follower's ability still trigger?
AYes, it will. This follower's ability is dependent on the original cost of the card played. Tomoe Murakami's original cost is 6, so it will trigger this follower's ability.
QIf I have multiple copies of this follower on my field, and I play a card that costs 5 or more, will each copy's ability trigger?
AYes, they will.
QIf I play a Quick card that costs 5 or more in an opponent's turn, will this follower's ability trigger?
AYes, it will. Per turn includes both your and your opponents' turns.