They probably specified that because there are other warlock invocations that do require you to use a spell slot.
They probably specified that because there are other warlock invocations that do require you to use a spell slot.
Time travels in divers paces with divers persons.
—As You Like It, III:ii:328
Chronos's Unalliterative Skillmonkey Guide
Current Homebrew: 5th edition psionics