Assassins' Mushroom Poison

When Assassins' Mushroom Poison enters the battlefield, put three -1/-1 counters on it. Whenever a creature equipped with Assassins' Mushroom Poison battles another creature, the equipped creature may put one or more -1/-1 counters on its enemy at the start of the battle.
Fungilocks' mushroom garden produces some specimens not fit for Earthlings' consumption.