#2. To build towards an anti-authority feud.

The spokes on the wheel have been turning for a while for a Reigns vs. Authority feud.
Roman Reigns made his move to SmackDown Live by attacking the Chairman of WWE, Vince McMahon. Conveniently, a few weeks ago, Shane McMahon turned heel on The Miz after losing the SmackDown Tag Team Championship to Jimmy and Jey Uso, making him a perfect candidate to align with Vince and represent the authority figure on TV
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On the latest episode of SmackDown Live, WWE teased an altercation between Shane and Reigns, before which Elias attacked Reigns from behind. The Elias feud might be a stepping stone for Reigns before he takes on another version of The Authority in the coming weeks - most probably at SummerSlam 2019.
WWE has been repeating the Authority angle for far too long and would be hoping that at least this one delivers.