Most played cards in Ninjas:

5 Decks
Ninja of the Deep Hours
20 copies - 4 average
Spellstutter Sprite
19 copies - 3.8 average
Ornithopter
17 copies - 3.4 average
Mistblade Shinobi
16 copies - 3.2 average
Force of Will
16 copies - 3.2 average
Standstill
12 copies - 2.4 average
Mutavault
12 copies - 2.4 average
Daze
11 copies - 2.2 average
11 copies - 2.2 average
Pithing Needle
10 copies - 2 average
Umezawa's Jitte
10 copies - 2 average
Snow-Covered Island
10 copies - 2 average
Cloud of Faeries
8 copies - 1.6 average
Annul
8 copies - 1.6 average
Relic of Progenitus
7 copies - 1.4 average
Mothdust Changeling
7 copies - 1.4 average
Snow-Covered Plains
6 copies - 1.2 average
Back to Basics
6 copies - 1.2 average
Higure, the Still Wind
6 copies - 1.2 average
Faerie Conclave
5 copies - 1 average