The Chronoclasmist

The Chronoclasmist enters the battlefield tapped
and doesn't untap on its controller's untap step.
Whenever the Chronoclasmist deals combat
damage to an opponent, its controller takes an
extra turn after this.
{u}{u}{r}{r}{r}{w}{w}: Untap the Chronoclasmist.
It regards no timeline or reality, weaving an existence
few others can comprehend.