I was playing in a ranked brawl. Opponent played Tarrian's Soulcleaver and was using mutagen tokens to get graveyard triggers on it. Rule 110.5 states that A token that’s in a zone other than the battlefield ceases to exist and rule 110.5g adds A token that has left the battlefield can’t move to another zone or come back onto the battlefield — if it would change zones, it remains in its current zone and ceases to exist the next time state-based actions are checked. Since you can't respond to the token leaving the battlefield, then the state-based action is not available. therefore, Tarrian's Soulcleaver shouldn't be getting graveyard triggers from tokens that cease to exist after removal.