entry point into his Cosmere books. My recommendation for reading order would be:
1. Start with the first Mistborn Series (Mistborn/The Final Empire, The Well of Ascension, The Hero of Ages)
2. Elantris
3. The Elantris/Mistborn related novellas from Arcanum Unbounded: Cosmere Collection (The Hope of Elantris, The Emperor's Soul, The Eleventh Metal)
4. Warbreaker
After those books and novellas, then I would recommend jumping into the Stormlight Archive.