Lightwalker

This creature has flying as long as it has a +1/+1 counter on it.

Plains

Thriving Heath

This land enters tapped. As it enters, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Bulwark Giant

When this creature enters, you gain 5 life.

Gird for Battle

Put a +1/+1 counter on each of up to two target creatures.

Trusty Retriever

When this creature enters, choose one —
• Put a +1/+1 counter on this creature.
• Return target artifact or enchantment card from your graveyard to your hand.

Battlefield Promotion

Put a +1/+1 counter on target creature. That creature gains first strike until end of turn. You gain 2 life. (A creature with first strike deals combat damage before creatures without first strike.)

Basri's Acolyte

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
When this creature enters, put a +1/+1 counter on each of up to two other target creatures you control.

Patron of the Valiant

Flying
When this creature enters, put a +1/+1 counter on each creature you control with a +1/+1 counter on it.

Cathars' Crusade

Whenever a creature you control enters, put a +1/+1 counter on each creature you control.

Secure the Scene

Exile target nonland permanent. Its controller creates a 1/1 white Soldier creature token.

Tempered Veteran

{W}, {T}: Put a +1/+1 counter on target creature with a +1/+1 counter on it.
{4}{W}{W}, {T}: Put a +1/+1 counter on target creature.

Siege Striker

Double strike (This creature deals both first-strike and regular combat damage.)
Whenever this creature attacks, you may tap any number of untapped creatures you control. This creature gets +1/+1 until end of turn for each creature tapped this way.

Makeshift Battalion

Battalion — Whenever this creature and at least two other creatures attack, put a +1/+1 counter on this creature.