Hero of the Games

Whenever you cast a spell that targets Hero of the Games, creatures you control get +1/+0 until end of turn.

Infuriate

Target creature gets +3/+2 until end of turn.

Arena Athlete

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

Young Pyromancer

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

Thriving Bluff

Thriving Bluff enters tapped. As it enters, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

Hearts on Fire

One or two target creatures each get +2/+1 until end of turn.

Crimson Wisps

Target creature becomes red and gains haste until end of turn. (It can attack and {T} this turn.)
Draw a card.

Cleon, Merry Champion

Double strike
Heroic — Whenever you cast a spell that targets Cleon, exile the top card of your library. You may play that card until the end of your next turn.

Roil Eruption

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Roil Eruption deals 3 damage to any target. If this spell was kicked, it deals 5 damage instead.

Uncaged Fury

Target creature gets +1/+1 and gains double strike until end of turn. (It deals both first-strike and regular combat damage.)

Weaver of Lightning

Reach (This creature can block creatures with flying.)
Whenever you cast an instant or sorcery spell, Weaver of Lightning deals 1 damage to target creature an opponent controls.

Goblin Dark-Dwellers

Menace (This creature can't be blocked except by two or more creatures.)
When Goblin Dark-Dwellers enters, you may cast target instant or sorcery card with mana value 3 or less from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead.

Akroan Crusader

Heroic — Whenever you cast a spell that targets Akroan Crusader, create a 1/1 red Soldier creature token with haste. (It can attack and {T} as soon as it comes under your control.)