Orochimaru's Forbidden Jutsu M-737 and correlating cards

"When you discard a card due to the effect of 1 of your ninja (cards), put a coin on this card" How does this work with a single effect but multiple discarded cards, like Zabuza N-1407 or Orochimaru N-1081 does it trigger per card discarded or in comparison to Vessel of Dreams M-736 "When you discard card(s) due to the effect of 1 of your ninja or missions, draw 1 and remove a coin from this mission" which definitely seems to trigger off of the instance instead of said amount of discarded cards.

Something else I noticed was that the mission has (cards) parenthesized, does this include ninjas and or ninja cards? or specifying only ninja cards I'm assuming its including ninjas and ninja cards. Was just wondering if the obvious answer is wrong!

one instance of an effect so if you discard 12 cards for 1 effect u only get 1 card