All the spell casting classes in D&D have their iconic spells. The wizard has fireball and magic missile. The cleric has cure wounds and turn undead (yeah yeah I know, not technically a spell). The druid has call lightning. Nothing quite says "Why yes nature is my mother and she's exceptionally displeased with you right now" more than one of the most concentrated destructive displays of nature's power directed at your person. Be afraid, for druids can make lightning strike twice. Or even more.
Yes, I'm aware of the typo. I'm too lazy to fix it.