MT EREBUS parsed as MTE REBUS, giving a nice rationale for why M T E are squished into a square. I've long wondered why we use the term "rebus" to describe "multiple letters jammed into a square" — I'm used to "rebus" describing a picture — but it's just one of those insidery crossword things.

I knew what MT EREBUS was! Honest! What, you don't believe me? I must insist that I … okay, fine. Never heard of it. Glad to learn what it was — southernmost active volcano, that's a cool fact — but boy, was it hard to parse a weird MTEREBUS string when EREBUS sounded so unfamiliar.
Some great theme phrases, FORT SUMTER, FARM TEAM, WISDOM TEETH, ASSAM TEA, WILLIAM TELL, TIM TEBOW all beautiful. I would have liked one more pair of themers like this — just three rebus squares felt a bit miserly — but where would you stick another? I suppose Jacob could have made the revealer (MTE)REBUS with another MTE square, but that would have been plain old mean!
Generally clean gridwork, just some minor CTA, RAHS, RRS type stuff. Not easy to do when you have to work around crossing pairs of themers. But I did feel that the grid was choked-off, with so many narrow passageways. Would have been great to get more of an open feel to the puzzle, with a couple more pieces of bonus long fill. Perhaps by taking out the black square between FDA and FORE, or GMC and ASP?
This would no doubt have introduced some more crossword glue into the fill, but oddly enough, that might have made for a more pleasurable solving experience in places. For instance, I got horribly stuck in the north section, unable to determine what [Anterior] could be. Short answers like FORE and FRAT can be tough to clue in challenging ways, so in Thursday puzzles, they often end up being frustratingly and opaquely difficult, without much of an a-ha moment to reward all your head-banging. (Didn't help that I held onto WRAP party for the longest time; sigh.)
Clever concept to parse MT EREBUS into MTE REBUS. I wonder if it'll be too crossword-insidery for some solvers, though.