Birthday Anna's power is basically the same as regular Anna; however, it takes 1 less Anna Tsum to power up her power (15 instead of 16) making her slightly better than the regular Anna. Her power will change random Tsums into Elsa Tsums. You can connect Anna and Elsa Tsums together to make chains and when one of the Elsa Tsums is cleared it will also clear surrounding Tsums.