Dio Brando, Heinous Interloper

If Dio Brando, Heinous Interloper is blocked, you
may pay half the blocker's mana value rounded
up in black and/or colorless mana to destroy it
before combat.
If Dio Brando is sent to the graveyard, instead
exile it and place a time counter on it at the start
of each player's turn.
If there are 5 or more time counters on Dio
Brando, return it to the battlefield transformed
into DIO, Emperor of The World.