Gird for Battle

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

Sunhome Stalwart

First strike (This creature deals combat damage before creatures without first strike.)
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

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.)

Swift Response

Parhelion Patrol

Flying
Vigilance (Attacking doesn't cause this creature to tap.)
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

Light of the Legion

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
When this creature dies, put a +1/+1 counter on each white creature you control.

Mikaeus, the Lunarch

Mikaeus enters with X +1/+1 counters on it.
{T}: Put a +1/+1 counter on Mikaeus.
{T}, Remove a +1/+1 counter from Mikaeus: Put a +1/+1 counter on each other creature you control.

Urdnan, Dromoka Warrior

When Urdnan enters, put a +1/+1 counter on target creature.
Whenever you attack, target attacking creature with a +1/+1 counter on it gains first strike until end of turn. If that creature has two or more +1/+1 counters on it, it gains double strike until end of turn instead.

Steadfast Sentry

Vigilance (Attacking doesn't cause this creature to tap.)
When this creature dies, put a +1/+1 counter on target creature you control.

Sandsteppe Outcast

When this creature enters, choose one —
• Put a +1/+1 counter on this creature.
• Create a 1/1 white Spirit creature token with flying.

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.

Banishing Light

When this enchantment enters, exile target nonland permanent an opponent controls until this enchantment leaves the battlefield.

Gavony Silversmith

When this creature enters, put a +1/+1 counter on each of up to two target creatures.