Heroic

Heroic is an ability word introduced in Theros. A creature with a heroic gives the controlling player powerful benefits every time he casts a spell that targets it. ^[1]

Rulings

A heroic ability triggers only when the creature's controller casts a spell that targets it, not when any other player does.
A heroic ability triggers whenever a player casts any spell that targets the heroic creature, including a spell that also targets another creature.
If a spell targets multiple creatures with heroic abilities, all of them trigger.
Activated abilities, such as equip, do not cause heroic abilities to trigger.
An instant or sorcery spell has a target if it includes the word "target" in its rules text.
Each Aura spell also has a target, indicated by its enchant ability.
Creature spells and other permanent spells (except for Auras) never have targets.
Heroic abilities will resolve before the spell that caused them to trigger.
Heroic abilities will trigger only once per spell, even if that spell targets the creature with the heroic ability multiple times.
Heroic abilities won't trigger when a copy of a spell is created on the stack or when a spell's targets are changed to include a creature with a heroic ability.

There is a total of 18 cards that involve heroic, which divide by color as such: