Frontline Medic

Battalion — Whenever Frontline Medic and at least two other creatures attack, creatures you control gain indestructible until end of turn.
Sacrifice Frontline Medic: Counter target spell with {X} in its mana cost unless its controller pays {3}.

Legion Loyalist

Haste
Battalion — Whenever Legion Loyalist and at least two other creatures attack, creatures you control gain first strike and trample until end of turn and can't be blocked by creature tokens this turn.

Oblivion Ring

When Oblivion Ring enters, exile another target nonland permanent.
When Oblivion Ring leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Plains

Odric, Master Tactician

First strike (This creature deals combat damage before creatures without first strike.)
Whenever Odric, Master Tactician and at least three other creatures attack, you choose which creatures block this combat and how those creatures block.

Lightning Mauler

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Lightning Mauler is paired with another creature, both creatures have haste.

Boros Elite

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

Slayers' Stronghold

{T}: Add {C}.
{R}{W}, {T}: Target creature gets +2/+0 and gains vigilance and haste until end of turn.

Aurelia, the Warleader

Flying, vigilance, haste
Whenever Aurelia attacks for the first time each turn, untap all creatures you control. After this phase, there is an additional combat phase.

Hanweir Lancer

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Hanweir Lancer is paired with another creature, both creatures have first strike.

Silverblade Paladin

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Silverblade Paladin is paired with another creature, both creatures have double strike.

Wojek Halberdiers

Battalion — Whenever Wojek Halberdiers and at least two other creatures attack, Wojek Halberdiers gains first strike until end of turn.

Mountain

Boros Charm

Choose one —
• Boros Charm deals 4 damage to target player or planeswalker.
• Permanents you control gain indestructible until end of turn.
• Target creature gains double strike until end of turn.

Firemane Avenger

Flying
Battalion — Whenever Firemane Avenger and at least two other creatures attack, Firemane Avenger deals 3 damage to any target and you gain 3 life.

Boros Guildgate

This land enters tapped.
{T}: Add {R} or {W}.

Clifftop Retreat

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