Blessing of Sanctuary

2nd-level Transmutation
Casting Time: 1 bonus action
Range: 30 feet
Components: VS
Duration: 1 minute

You imbue the target with extraordinary resilience, temporarily hardening them against damage from all attacks. Until the spell ends, anytime anyone rolls damage dice against the target, reroll any results on damage dice that come up with the maximum result from that die. You must use the new result. Additionally, critical hits scored against the blessed target become normal hits.
A creature can only have one Blessing spell on them at a time.
At Higher Levels. When you cast this spell at 3rd level or higher, you can target one additional creature for each slot level above 2nd.

Source: Homebrew