The Elven Battalion Hero, Tactician, has an ability, Banner, which is possibly the most versatile ability in the game. Any other elven hero can right click a nearby banner to add their own effects.
 Banner Effects
Adds Brilliance Aura with ? mana/s regeneration.
Adds Trueshot Aura with +? ranged damage.
Adds Immolation with ? dmg/s.
Creates a Thunderstorm that deals ? dmg to a unit every ? sec in ? aoe.
Causes banner to explode upon death, dealing ? damage. Triggers Infiltrator's explosives.
Adds Mockery Aura with -? damage for enemies.
Adds an Aura that decreases enemys armor by 2 to 7.
Causes 3 small flaming stones to swirl around the banner, dealing ? damage.
Adds Haste Aura, increasing movement speed by ? and attack speed by ?.