Valor

Valor is a battle skill keyword that gives a unit +1/+1 for each unit blocking it. It was introduced in Revelations.

Find cards with Valor in its category page.

Rules

Valor's rules text, from the in-game description:

When a unit with Valor is blocked, it gets +1/+1 this turn for each unit blocking it.

Details

Valor is triggered whenever any unit blocks the unit with Valor.

While this will typically happen in normal combat, it is also triggered by making a KillerKiller:
May be exhausted one time to attack any enemy unit. attack with the Valor unit (which forces the attacked unit to block). If the Killer attack is redirected to an ambushingAmbush:
Can be played to block an enemy attack or at the end of their turn. unit, Valor is triggered another time.

The strength and health of units with Valor will automatically increase and decrease as you assign and unassign blockers to them, but won't be locked in until you finalize blockers.

Notes

Valor was revealed in the Revelations' spoiler-season mechanic reveal article for the keyword.