Well, maybe is the translation to English, but I was thinking more in a "Blow up" than a "fire explosion", so when a tree explodes, it didn't hurt enough other things to making then explode too.
At first, I didn't think on "chain explosion", but you give me the idea that this world could have some items designed to hurt your enemies when it blows up, like a spike maze that throw spikes when explodes, spike shields, etc