| Brain-scan letters |
| Starchy tubers |
| All, e.g., for this answer's last six letters? |
| Archaeologist's letters |
| Organizations with Greek letters |
| Confusing statements ... and a hint to the circled letters |
| Surprises unpleasantly, and a hint to each starred answer's first two + last two letters |
| Attend a party uninvited ... and a literal hint to five sets of circled letters |
| Accompaniers of cover letters: Abbr. |
| Adjust space between letters, in printing |
| Whatever it takes ... as hinted at in the arrangements of black squares around the circled letters |
| Personal letters |
| Letters from the family? |
| Bounced-check letters |
| Retirement plan letters |
| Letters preceding an assumed name |
| ICU instruction letters |
| Chemist's glass tube |
| Artistic place for tiny letters? |
| Filling station letters? |
| With "a," someone undesirable ... and what's found in the circled letters? |
| And so forth" letters |
| Alternate identity letters |
| Agrarian structure, and a hint to the circled letters |
| About to shotgun this tube of cookie dough and binge-watch 'Breaking Bad' backwards so it seems like Walt gets lame #____ |
| Memo letters for "I need it now! |
| Adjust spacing between letters, in printing |
| Creepy pencil-and-paper "game" popularized in 2015 via YouTube and Twitter (and basis of the theme answers) |
| Cyber-opinion letters |
| Laboratory tube (Var.) |