Ingenious Leonin

{3}{W}: Put a +1/+1 counter on another target attacking creature you control. If that creature is a Cat, it gains first strike until end of turn. (It deals combat damage before creatures without first strike.)

Pacifism

Enchant creature
Enchanted creature can't attack or block.

Thriving Heath

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

Leonin Vanguard

At the beginning of combat on your turn, if you control three or more creatures, this creature gets +1/+1 until end of turn and you gain 1 life.

Brimaz, King of Oreskos

Vigilance
Whenever Brimaz, King of Oreskos attacks, create a 1/1 white Cat Soldier creature token with vigilance that's attacking.
Whenever Brimaz blocks a creature, create a 1/1 white Cat Soldier creature token with vigilance that's blocking that creature.

Leonin Scimitar

Equipped creature gets +1/+1.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Plains

King of the Pride

Basri's Acolyte

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

Dawnwing Marshal

Flying
{4}{W}: Creatures you control get +1/+1 until end of turn.

Savannah Lions

Take Up the Shield

Put a +1/+1 counter on target creature. It gains lifelink and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Impeccable Timing

Impeccable Timing deals 3 damage to target attacking or blocking creature.

Leonin of the Lost Pride

When Leonin of the Lost Pride dies, exile target card from an opponent's graveyard.