Kallento's Infection

{g}{t}: Create a 2/1 Black and Green Plant Zombie with Vigilance.
When an Elf comes into play, Plant Zombie Creatures you control gain Vigilance
and +1/+0.
"This "Elf Foe" is no threat to us, but apparently a very dear one to elves. He could be very useful."
-Last words of an thieving wizard