Blue
Ravenous Bugblatter Beast of Traal
There's a simple homebrew idea we employ for 5E - 'Take the Attack'.
Take the Attack (Reaction) : When an ally adjacent to you would be attacked by an enemy, you can move in the way of the blow, and the attack roll targets you instead.
We make this simple option so literally anyone, from any class, can have heroic 'save the squishy' moments. Stick the ability on a Full-Plate and Shield-wearing defender, and it is a significant boon, especially after magic items are taken into account.
This seems to step all over the Protection fighting style. Now anyone can do something, without the opportunity cost of taking that fighting style over another. Protection fighting style can be a bit better and a bit worse (less chance anyone is hit, but it's still the original squishy low-AC target), but it's often considered one of the weaker fighting styles already. Now, where it's on-par or barely better than what everyone can naturally do I can't see any reason for people to take it.