When you control no other creatures, sacrifice this creature.
Emperor Crocodile’s ability will trigger if you don’t control another creature, even if it’s only for a brief moment during the resolution of another spell or ability (such as that of Brago, King Eternal).
The ability only checks if you control no other creatures at the time it triggers. It does not check again on resolution, so gaining control of a creature before then will not save Emperor Crocodile.
