As long as you have seven or more cards in hand, Deathmask Nezumi gets +2/+1 and has fear. (It can't be blocked except by artifact creatures and/or black creatures.)

, Sacrifice a creature: Target player discards a card. Activate only as a sorcery.

Menace

When Nezumi Freewheeler enters the battlefield, each player mills three cards. (To mill three cards, a player puts the top three cards of their library into their graveyard.)

: Transform Nezumi Freewheeler. Activate only as a sorcery. ( can be paid with either or 2 life.)

When Nezumi Informant enters the battlefield, each opponent discards a card.

Ninjutsu (, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)

When Nezumi Prowler enters the battlefield, target creature you control gains deathtouch and lifelink until end of turn.

Bushido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.)

, : Target opponent discards a card. Then if that player has no cards in hand, flip Nezumi Shortfang.

Rat offering (You may cast this spell any time you could cast an instant by sacrificing a Rat and paying the difference in mana costs between this and the sacrificed Rat. Mana cost includes color.)

Whenever a permanent is put into an opponent's graveyard, that player loses 1 life.