Gates to the Unknown

{t}: Add {c} to your mana pool, then roll a six sided die. If you get a 1-4, then you lose 1 life. If you get a 5-6, then create a 1/1 colorless Shapeshifter creature token with changeling. (That creature is all creature types.)
Sometimes closed, sometimes open. The Gate to the Unknown is, well, unknown with a lot of things, like what those things are and why they come out of the gate. Sometimes they attack, sometimes they rub up against your leg wanting to be pet, like a housecat.