Mare of the Undying Blaze

When Mare of the Undying Flames enters the battlefield, for each mountain you control, add
that many mountains to the battlefield.
Mare of the Undying Flame's power and
toughness equal to the number of mountains you control.
{5}{r}{r}, {t}: If a source you control would deal
damage to a permanent or player, it deals double
that damage to that permanent or player instead.