Rum, Giant of the North

Menace, Haste, Trample
When Rum, Giant of the North enters the battlefield, he fights target creature.
Whenever Rum, Giant of the North destroys a creature, create a colourless Treasure artifact token with "{t}, Sacrifice this artifact: Add one mana of any colour to your mana pool".
Then if you control four or more Treasure tokens, transform Rum, giant of the North