In rulebook is written:

"When a non-Flying unit moves into a hex containing an inferno marker, that unit must immediately end its movement and suffer 1 damage. The inferno marker is then removed from the game board."

It's meaning that Inferno marker can be remove only when player move on hex containing this marker ? During retreat this marker still remain on game board and not suffer any additional damage (obviously one damege per each flag on dice during retreat).

Confirm if I understand someething wrong.

The Inferno marker is removed as soon as any non-flying unit enters the hex, whether it's a willful move or from retreating. Even though it's removed, it still prevents the retreating unit from resolving any additional retreats from that attack. If it's attacked again and forced to retreat, it can.

For example, a Mountain Giant is forced to retreat 3 times. It retreats into an inferno marker and takes 1 damage, then the inferno marker is removed. The Giant then takes 2 more points of damage from the other 2 retreats it can't resolve because the inferno stops further movement that attack. The same turn, another attack against the Giant forces it to retreat, which it can resolve since this is a separate attack.

Perfect answer, Daveman

Thank's for explanation. One more question. It's mean that non-flying units during retreat does not stop on hex with this marker ?

If a flying unit enters a hex with an inferno marker (moving or retreating), nothing happens to the unit or the inferno marker. That unit just flies over it.

If any other (non-flying) unit enters a hex with an inferno marker (moving or retreating), it takes 1 damage, removes the marker, and must end it's movement. If it's retreating it must end it's movement and suffer damage for any remaining retreat results that combat. It can retreat if it's forced to from a later attack that turn.