Lightwalker

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

Reprobation

Enchant creature
Enchanted creature loses all abilities and is a Coward creature with base power and toughness 0/1. (It keeps all supertypes but loses all other types and creature types.)

Heliod's Pilgrim

When this creature enters, you may search your library for an Aura card, reveal it, put it into your hand, then shuffle.

Answered Prayers

Whenever a creature you control enters, you gain 1 life. If this enchantment isn't a creature, it becomes a 3/3 Angel creature with flying in addition to its other types until end of turn.

Squadron Hawk

Flying
When this creature enters, you may search your library for up to three cards named Squadron Hawk, reveal them, put them into your hand, then shuffle.

Shoulder to Shoulder

Support 2. (Put a +1/+1 counter on each of up to two target creatures.)
Draw a card.

Battalion Foot Soldier

When this creature enters, you may search your library for any number of cards named Battalion Foot Soldier, reveal them, put them into your hand, then shuffle.

Snow-Covered Plains

Idyllic Grange

({T}: Add {W}.)
This land enters tapped unless you control three or more other Plains.
When this land enters untapped, put a +1/+1 counter on target creature you control.

Ainok Bond-Kin

Outlast {1}{W} ({1}{W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each creature you control with a +1/+1 counter on it has first strike.

Silverflame Ritual

Put a +1/+1 counter on each creature you control.
Adamant — If at least three white mana was spent to cast this spell, creatures you control gain vigilance until end of turn.

Legion Conquistador

When this creature enters, you may search your library for any number of cards named Legion Conquistador, reveal them, put them into your hand, then shuffle.