Star Reef - 5 is the fifth level of the Star Reef. You should notice a pattern here- the levels for Star Reef alternate between Normal Battle and Wave Battle.
You have to fight 1 Banshee and 2 Stinky Zombies. Each enemy's stats are shown below.
Choose Matilda in Druid, Bomb in Cannoneer and The Blues in Rogues. Heal with Matilda if the birds' healths are not full and if they're full, attack with her. Then attack with the others(All attacks focus on the Stinky Zombies first, then the Banshee). Use the Rage Chili on Matilda when it is full. Repeat this over until you win or either lose.
Stinky Zombie and Banshee can poison you, so it's best to defeat them.