Maximize Velocity

Target creature gets +1/+1 and gains haste until end of turn.
Jump-start (You may cast this card from your graveyard by discarding a card in addition to paying its other costs. Then exile this card.)

Lava Coil

Lava Coil deals 4 damage to target creature. If that creature would die this turn, exile it instead.

Tajic, Legion's Edge

Haste
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Prevent all noncombat damage that would be dealt to other creatures you control.
{R}{W}: Tajic, Legion's Edge gains first strike until end of turn.

Mountain

Intervention

Intervention deals 3 damage to any target and you gain 3 life.

Integrity

Target creature gets +2/+2 until end of turn.

Integrity // Intervention

Torch Courier

Haste
Sacrifice Torch Courier: Another target creature gains haste until end of turn.

Healer's Hawk

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Plains

Precision Bolt

Precision Bolt deals 3 damage to any target.

Boros Challenger

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
{2}{R}{W}: Boros Challenger gets +1/+1 until end of turn.

Legion Warboss

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
At the beginning of combat on your turn, create a 1/1 red Goblin creature token. That token gains haste until end of turn and attacks this combat if able.