Silent-Blade Oni | Magic: The Gathering
Formats Silent-Blade Oni is Legal in
Official Oracle Text for Silent-Blade Oni
Whenever Silent-Blade Oni deals combat damage to a player, look at that player's hand. You may cast a nonland card in it without paying that card's mana cost.
Official Rulings for Silent-Blade Oni
6/1/2012 : The nonland card you cast via the triggered ability is cast as part of the resolution of that ability. Timing restrictions based on the card's type are ignored. Other restrictions, such as "Cast [this card] only during an opponent's turn," are not.
6/1/2012 : If you cast a card without paying its mana cost, you can't pay any alternative costs, such as evoke or the alternative cost provided by the morph ability. If it has in its mana cost, X must be 0. However, you can pay optional additional costs, such as kicker, and you must still pay mandatory additional costs, such as the one on Fling.