Rubilax, the Unleashed

Trample
Rubilax, the Unleashed attacks each combat if able.
When Rubilax deals combat damage to a player
you may discard a card then draw two cards.
At the beginning of your end setp, if Rubilax, the Unleashed did not deal combat damage to a player, exile Rubilax, then return him to the battlefield transformed under his owner's control.