Caustic, Toxic Trapper

Whenever Caustic, Toxic Trapper enters the battlefield, create a 0/1 Gas tank token with
"Whenever this creature dies in combat, if target creature does not have a -1/-1 counter then you may place a -1/-1 counter on that creature." and defender.
{b}{g}: Create a 0/1 Gas tank token with "Whenever this creature dies in combat, if target creature does not have a -1/-1 counter then you may place a -1/-1 counter on that creature." and defender.
{2}{b}{b}{g}: All other creatures get -4/-4 until your
next