Arena Athlete

Heroic — Whenever you cast a spell that targets Arena Athlete, target creature an opponent controls can't block this turn.

Sudden Breakthrough

Target creature gets +2/+0 and gains first strike until end of turn.
Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Accelerate

Target creature gains haste until end of turn.
Draw a card.

Akroan Conscriptor

Heroic — Whenever you cast a spell that targets Akroan Conscriptor, gain control of another target creature until end of turn. Untap that creature. It gains haste until end of turn.

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Playful Shove

Playful Shove deals 1 damage to any target.
Draw a card.

Loyal Apprentice

Haste
Lieutenant — At the beginning of combat on your turn, if you control your commander, create a 1/1 colorless Thopter artifact creature token with flying. That token gains haste until end of turn.

Rosnakht, Heir of Rohgahh

Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)
Heroic — Whenever you cast a spell that targets Rosnakht, Heir of Rohgahh, create a 0/1 red Kobold creature token named Kobolds of Kher Keep.

Imodane, the Pyrohammer

Whenever an instant or sorcery spell you control that targets only a single creature deals damage to that creature, Imodane deals that much damage to each opponent.

Bill Potts

Whenever you cast an instant or sorcery spell that targets only Bill Potts or activate an ability that targets only Bill Potts, copy that spell or ability. You may choose new targets for the copy. This ability triggers only once each turn.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Akroan Line Breaker

Heroic — Whenever you cast a spell that targets Akroan Line Breaker, Akroan Line Breaker gets +2/+0 and gains intimidate until end of turn. (It can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Ancestors' Aid

Krenko, Tin Street Kingpin

Whenever Krenko, Tin Street Kingpin attacks, put a +1/+1 counter on it, then create a number of 1/1 red Goblin creature tokens equal to Krenko's power.

Akroan Crusader

Heroic — Whenever you cast a spell that targets Akroan Crusader, create a 1/1 red Soldier creature token with haste.

Ancestral Anger

Target creature gains trample and gets +X/+0 until end of turn, where X is 1 plus the number of cards named Ancestral Anger in your graveyard.
Draw a card.

Labyrinth Champion

Heroic — Whenever you cast a spell that targets Labyrinth Champion, Labyrinth Champion deals 2 damage to any target.

Goblin Traprunner

Whenever Goblin Traprunner attacks, flip three coins. For each flip you win, create a 1/1 red Goblin creature token that's tapped and attacking.

Satyr Hoplite

Heroic — Whenever you cast a spell that targets Satyr Hoplite, put a +1/+1 counter on Satyr Hoplite.

Zada, Hedron Grinder

Whenever you cast an instant or sorcery spell that targets only Zada, Hedron Grinder, copy that spell for each other creature you control that the spell could target. Each copy targets a different one of those creatures.

Blazing Crescendo

Target creature gets +3/+1 until end of turn.
Exile the top card of your library. Until the end of your next turn, you may play that card.

Rodeo Pyromancers

Whenever you cast your first spell each turn, add {R}{R}.

Kiln Fiend

Whenever you cast an instant or sorcery spell, Kiln Fiend gets +3/+0 until end of turn.

Fists of Flame

Draw a card. Until end of turn, target creature gains trample and gets +1/+0 for each card you've drawn this turn.