When Stangg enters, create Stangg Twin, a legendary 3/4 red and green Human Warrior creature token. Exile that token when Stangg leaves the battlefield. Sacrifice Stangg when that token leaves the battlefield.
If Stangg leaves the battlefield before its ability has resolved, that ability will still create a Stangg Twin token, but its delayed triggered ability that exiles the token will never have a chance to trigger. That token will remain on the battlefield.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.