Ineed a topic sentence for war of worlds ! ?

Topic Sentence : Today i will tell you about war of world. War of worlds is ... ( whatever it is)

Conclusion : Now you know about the war of worlds.

I know this may be late but I hope it might help for future references. So, this is what I would suggest; 
           Perfecting the skill of writing topic sentences is essential to successful writing. A topic sentence usually comes at the beginning of a paragraph, and lets your reader know what to expect from each paragraph. Think of it as a preview for a movie or a headline in a newspaper, highlighting the "main point" that's to come in the paragraph. Make sure your topic sentences are up to par, and the rest of your writing will feel like a breeze.