Synchro Rules

To put a Synchro creature onto your battlefield
from outside the game, sacrifice creatures you
control whose total converted mana cost equals
the Synchro creature your trying to put on the
battlefield, and one sacrifice must be a Tuner
creature. To do so, you must also "declare a
Synchro" as a sorcery. Synchro creatures enter
the battlefield with an amount of Synchro
Counters equal to the number of creatures
sacrificed this way.