Stuck with the moth priest

I've killed everything up to the point of taking down the moth priest. It says I need to talk to him but it won't let me. And Serena keeps think...

Is Tall-Nut worth its price?

Tall nut is one of my most used plants due to its high durability and the ability to block jumping/vaulting zombies. However, 2 wall nuts can do the same ...