Lephantis, The Millennia

Infect
Devour 2 (As this enters the battlefield, you may sacrifice any number of creatures. This creature enters
the battlefield with 2 +1/+1 counters on it for each of
those creatures.)
If you control 10 or more infested permanents,
all {b} in Lephantis' mana cost become {p/b}. If you
cast Lephantis by paying 6 or more life this way,
each opponent sacrifices a permanent.