Tactical Timer has a set of features for handy time management and alarms. Its like usual Timer with extra features, its using Actions, Each Action has a Begin and an End, hence each Action has 2 alarms(if you set the alarms for same time then it will be like usual Timer), also counting how much time remains until Begin or until End of Action.
Make sure you allow it to run in background to be able to fire alarms, its not consuming much battery.