You learn one Eldritch Invocation option of your choice from the warlock class. If the invocation has a prerequisite, you can choose that invocation only if you’re a warlock and only if you meet the prerequisite.
Whenever you gain a level, you can replace the invocation with another one from the warlock class.
Eldritch Mind
You have advantage on Constitution saving throws that you make to maintain your concentration on a spell.