Forbidden Arts of the Gishki

Sacrifice any number of creatures and/or force
any number of your opponents to sacrifice a
number of target nontoken creatures with total
mana value X, where X is the Ritual Summon
value of a Gishki Ritual creature card in your
hand or command zone. Cast that creature. That creature enters the battlefield with Y -1/-0
counters on it, where Y is half that creature's
power, rounded down.
Skip your combat phase this turn.