Ninjutsu is a fair deck that does well against other fair decks, counterspell-based controls and any creature-based decks. It is not easy to pilot, and proper decisions are required at all times. The deck can also race combos with some sideboard support. It is not competitive, and should be played for fun.
Strengths are a potent card advantage engine, and the fact that ninjas make it to the battlefield via an activated ability bypassing most counterspells. The deck playstyle is primarily aggro, with ability to disrupt hands via discard, and ability to control opponent's creature board presence.
Generate card advantage with Thalakos Seer, Baleful Strix and Ingenious Infiltrator. The main wincon often happens around turn 6-7, and Yuriko, the Tiger's Shadow is your best tool here. Set up a surprise swing to the face, or a strategically clone a large threat with Sakashima's Student. Beware of Karakas, as it can bounce Yuriko.
By far the biggest threat is instant speed removal (bolts, decays, swords, punishing fire), and mass wipes (terminus, toxic deluge, golgari charm), which you are supposed to handle through card advantage. Try not to overextend the board and trade 2-for-1 (through drawing cards all the time).
Notes on sideboard: a potent package against combo decks.
