Brace

You touch one willing creature. For the duration, the target, as a bonus action, can brace itself for one attack each round. When attacked for the first time, the target can attempt to roll a reaction in order to absorb some of the impact of the attack. This spell only activates on a hit on the target. On successful CON Save against the Hit Die, the target reduces the damage taken by 1d8.

Once the caster reaches 5th level, increase the resisted damage by 1d8. The same for 11th and 17th level.