MTG Boros Mice Deck by Nessin

Offspring {2} (You may pay an additional {2} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.) Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, Mice you control get +1/+0 until end of turn.

Whenever one or more other Rabbits, Bats, Birds, and/or Mice you control enter, scry 1. Other Rabbits, Bats, Birds, and Mice you control get +1/+1.

Haste Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.) Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, exile the top card of your library. Until end of turn, you may play that card.

Offspring {2} (You may pay an additional {2} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.) At the beginning of combat on your turn, target Mouse you control gains your choice of double strike or trample until end of turn.

Other Mice you control get +1/+1. When Mabel enters, create Cragflame, a legendary colorless Equipment artifact token with "Equipped creature gets +1/+1 and has vigilance, trample, and haste" and equip {2}.

Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, look at the top five cards of your library. You may reveal a creature card with mana value 3 or less from among them. You may put it onto the battlefield if it's your turn. If you don't put it onto the battlefield, put it into your hand. Put the rest on the bottom of your library in a random order.

Flash Enchant creature you control As long as this Aura entered this turn, enchanted creature has hexproof. Enchanted creature gets +1/+1.

Enchant creature you control When this Aura enters, exile target nonland permanent an opponent controls until this Aura leaves the battlefield. Enchanted creature gets +1/+0 and has lifelink and ward {2}.

Gift a Food (You may promise an opponent a gift as you cast this spell. If you do, they create a Food token before its other effects. It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.") Target creature you control gets +2/+2 until end of turn. If the gift was promised, that creature also gains indestructible until end of turn.

Kicker {4} (You may pay an additional {4} as you cast this spell.) Burst Lightning deals 2 damage to any target. If this spell was kicked, it deals 4 damage instead.

{T}: Add {C}. {T}: Add {W}. Spend this mana only to cast a creature spell. {1}{W}, {T}, Sacrifice this land: Look at the top six cards of your library. You may reveal a Bat, Bird, Mouse, or Rabbit card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

({T}: Add {W}.)

({T}: Add {R}.)

{T}: Add {C}. {T}: Add {R}. Spend this mana only to cast a creature spell. {R}, {T}: Target Lizard, Mouse, Otter, or Raccoon you control gets +1/+0 and gains haste until end of turn. Activate only as a sorcery.

This land enters tapped unless you control two or fewer other lands. {T}: Add {R} or {W}.

This land enters tapped. {T}: Add {R} or {W}. {1}{R}{W}: This land becomes a 2/2 red and white Ox creature until end of turn. It's still a land. Whenever this land attacks, put a +1/+1 counter on target creature you control.

({T}: Add {R} or {W}.) As this land enters, you may pay 2 life. If you don't, it enters tapped.

{T}: Add {W}. {T}: Add {R}. Activate only if you control a Mountain or a Plains.