The Devil you know

On every killing blow of a sentient creature add a charge, all charges reset at the end of combat.
{1}: 1d6 additional weapon damage to target
if you miss you take the damage
{2}: As a reaction when targeted by a spell attack
make an ability check using your spell casting
ability DC10 + the spells level on success
reflect the spell back at the attacker
{x}: But do you really know me?