Voros, Champion of Exile

Players can't gain life during your turn.
When Voros, Champion of Exile attacks, you may
pay X life. Voros, Champion of Exile gets +X/-X
until end of turn. If X is 3 or more, Voros gains
first strike and trample until end of turn. If X is 6
or more, Voros gains menace until end of turn.
Whenever a creature blocks Voros, Champion of Exile, put a -1/-1 counter on that creature.