I'll go ahead and put down a banner design that I recently came across, and seemed like a nice one as well:
Start with a black base banner, and add the following:
- White fess (middle horizontal stripe)
- Red pale (middle vertical stripe)
- Red chevron (upside down V, with banner underneath it)
- Red inverted chevron (regular V, with banner underneath it)
- Red saltire (X-shape)
This makes you a nice Deadpool banner!