Bloodshed by Nightfall

Samurai cards in your hand and Samurai
creatures you control have Ninjutsu {x}, where X
is their converted mana cost.
Whenever a creature with Ninjutsu enters the
battlefield, it gets +2/+0 until end of turn.
"Honor does not win wars, but bloodshed will not win
you friends." - Zetsumasa The Cruel