At the beginning of each upkeep, create a 1/1 red and green Dragon creature token with flying and devour 2. (As the token enters the battlefield, you may sacrifice any number of creatures. It enters the battlefield with twice that many +1/+1 counters on it.)
Putting a token creature with devour onto the battlefield works the same as putting any other creature with devour onto the battlefield. The token may devour Dragon Broodmother itself!
In a Two-Headed Giant game, Dragon Broodmother’s second ability triggers only once at the beginning of each team’s upkeep, not once for each player. You’ll get one Dragon token at the beginning of your team’s upkeep and one Dragon token at the beginning of the opposing team’s upkeep.