Heralth, Tiefling King

Whenever a tiefling you control deals combat
damage, if that damage was dealt to a creature it
instead deals twice that much damage, if a player
was dealt damage this way untap it.
If one or more Tieflings were untapped there is
an additional combat phase after this one. Only
creatures untapped this way can attack during
that combat. This ability triggers only once each
turn.