Oath of the Defender

As an additional cost to cast this spell, tap an
untapped legendary creature you control.
Enchant legendary creature
Prevent all damage that would be dealt to yourself
or to creatures you control other than enchanted creature.
"I do not love the bright sword for its sharpness, nor
the arrow for its swiftness, nor the warrior for his glory.
I love only that which they defend." -J.R.R. Tolkien