Hyacidus

The Hyacidus is one of the functional flora featured in Botania. The Hyacidus will, when supplied with Mana, poison nearby mobs and bring them down to 1 health point.

Do note that Hyaciduss are not found naturally and must be planted by a player.

The tooltip carries a reference to Pokemon, on the fact that Steel Type pokemon are completely immune to any attack of the poison type.