Might of the Marilith

You’ve manifested some of the power of a marilith, granting you the following benefits:

Reactive. You get a special reaction that you can take once on every creature’s turn, except your turn. You can use this special reaction only to make an opportunity attack with a sword or to take the parry reaction, and you can’t use it on the same turn that you take your normal reaction.

Parry. When you are wielding a dagger or a sword with which you are proficient and another creature hits you with a melee attack, you can use your reaction to add your proficiency bonus to your AC for that attack, potentially causing the attack to miss you.