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.

Heroic Reinforcements

Create two 1/1 white Soldier creature tokens. Until end of turn, creatures you control get +1/+1 and gain haste. (They can attack and {T} this turn.)

Sunhome Stalwart

First strike
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

Chance for Glory

Creatures you control gain indestructible. Take an extra turn after this one. At the beginning of that turn's end step, you lose the game.

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

Abzan Falconer

Outlast {W} ({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 flying.

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.

Plains

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.)

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.

Goblin Banneret

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
{1}{R}: Goblin Banneret gets +2/+0 until end of turn.