Ninjas are one of the most interesting creature types in all of MTG
Getting benefits for opponents doing things is usually whites thing (Monologue TaxMonologue Tax, Charismatic ConquerorCharismatic Conqueror, Smothering TitheSmothering Tithe, etc.), but this is actually a callback to the red card Harsh MentorHarsh Mentor, which deals two damage to opponents for using activated abilities
If I speculate that the card is going to rise, I may offer upwards of 70% for certain cards such as Voice of Resurgence
(1) BONUS booster pack of 12 randomized cards
You can also group your cards by rarity, card type, or price
It goes on the stack after they've drawn and looked at all the cards and finished resolving the spell or ability that caused them to draw cards