Elemental Battle Magic

Your mastery of elemental magic has increased and you have become an expert at using elemental effects in battle.  When you use any spell that has an elemental damage type, you can use the spell without expending a spell slot. The spell must have a damage type of fire, cold, acid, lightning, or thunder and require one action to cast.  You may cast the spell as a bonus action or reaction, rather than a standard action. This allows you to cast the spell at any time as a reaction as long as you have not already used a reaction before your next turn, or as an additional action during your turn.  You may only use this power once before requiring a short or long rest to use it again.