Mountain Hide (Goliath Racial Feat)

Your flesh is as unyielding to weapons, projectiles and elemental magic as the side of a mountain. You gain the following benefits:

• Increase your Constitution score by 1, to a maximum of 20.
• When a creature you can see hits you with an attack roll, you can use your reaction to force that creature to reroll and accept the outcome of the second die. Once you use this ability, you can’t use it again until you roll initiative at the start of combat or until you finish a short or long rest.