Tyranid Harridan

Flying
Ravenous (You may sacrifice any number of
untapped lands as an additional cost to cast this
creature, if you do put a +1/+1 counter on it and
reduce its cost by {1} for each land sacrificed.)
Whenever a creature you control with a counter
on it deals combat damage create a 1/1 Blue
Tyranid Gargoyle creature token with Flying.