The Thunderboar is a large magical boar that was introduced in "Flute Spell."
Huntress Wizard, Finn and Jake were after one of it's tusks when it hits at tree and tells Finn that he could have asked for a tusk instead of chasing and ripping the tusk off it.
The Thunderboar has a torso of dark cloud and 2 white tusks on the front
When feeling threatened, the Thunderboar can emit cloud particles from it's dark-clouded back and also lighting strikes. It also has the ability to electrify it's tusks and regenerate it when it's damaged.