Azorius Arrester

When Azorius Arrester enters, detain target creature an opponent controls. (Until your next turn, that creature can't attack or block and its activated abilities can't be activated.)

Bladed Ambassador

Bladed Ambassador enters with an oil counter on it.
{1}, Remove an oil counter from Bladed Ambassador: Bladed Ambassador gains indestructible until end of turn.

Fresh-Faced Recruit

During your turn, Fresh-Faced Recruit has first strike.

Boros Elite

Battalion — Whenever Boros Elite and at least two other creatures attack, Boros Elite gets +2/+2 until end of turn.

Lightning Helix

Lightning Helix deals 3 damage to any target and you gain 3 life.

Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Plains

Mountain

Boros Guildgate

Boros Guildgate enters tapped.
{T}: Add {R} or {W}.

Aerial Boost

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Target creature gets +2/+2 and gains flying until end of turn.

Abrade

Choose one —
• Abrade deals 3 damage to target creature.
• Destroy target artifact.

Blind Obedience

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Artifacts and creatures your opponents control enter tapped.

Bulwark Giant

When Bulwark Giant enters, you gain 5 life.

Burn Bright

Creatures you control get +2/+0 until end of turn.

Clifftop Retreat

Clifftop Retreat enters tapped unless you control a Mountain or a Plains.
{T}: Add {R} or {W}.