Most played cards in Ninjas:

2 Decks
Spellstutter Sprite
8 copies - 4 average
Ninja of the Deep Hours
8 copies - 4 average
Spell Snare
7 copies - 3.5 average
Mutavault
7 copies - 3.5 average
Echoing Truth
7 copies - 3.5 average
Vendilion Clique
6 copies - 3 average
Negate
6 copies - 3 average
4 copies - 2 average
Hurkyl's Recall
4 copies - 2 average
Mana Leak
4 copies - 2 average
Trickbind
4 copies - 2 average
Brain Freeze
4 copies - 2 average
Umezawa's Jitte
4 copies - 2 average
Mistblade Shinobi
4 copies - 2 average
Ancestral Vision
4 copies - 2 average
Ornithopter
4 copies - 2 average
Mothdust Changeling
4 copies - 2 average
Seat of the Synod
3 copies - 1.5 average
Tormod's Crypt
3 copies - 1.5 average
Sower of Temptation
3 copies - 1.5 average