Defensive Shield Stance

You have practiced wielding shields giving you and rigid defensive stance. You can use a bonus action to go into your stance gaining the following:

• Lose half your speed.
• While wielding a shield you gain +1 to AC.
• When a creature within 5m attacks you and misses you can use your reaction to make an melee attack with your shield against that creature.
• The shield bash at level 1 does 1d4 of damage. Increases to 1d6 at level 7 and 1d8 at level 14. (If the shield used has a damage value, use it instead)
• Shield bash uses strength modifier and proficiency bonus on the attack roll and strength modifier on your damage roll.

All bonuses only apply in combat, while wielding a shield, and don't apply if you are surprised.