But wouldn't "@battery 20staple14 correct#horse" dodge a dictionary cracker? I have no idea how this works, so I'm genuinely curious.
Partially. But a good password cracker mixes things up. Also, while some things look more obscure that others, this is just a human thing. To measure the actual security you would use what is called "entropy": it essentially measures how likely that string is to occur by chance. But note that "by chance" does not mean "just roll a dice for each letter", but "how often does it appear in nature" (where "nature" is some setting you use, e.g. "all data on the internet"). Thus your dice show letters, but also words or other common sequences, each with their own probability coming from reality.
The string "battery correct horse staple" has pretty low entropy as it, as demonstrated by this thread, occurs quite often. The string "quantum dwarf house thorn" would be much better (but lost a lot due to now being mentioned here). For similiar reasons, using 100 consecutive letters from your book of choice is not much better than using 1000 consecutive letters instead: both appeared at least once, and probably the same number of times each, making them almost equally good.
On a similiar matter, adding just some numbers at the beggining and end of a password does not have any more effect than just adding one or two english words at the end, unless the added words are in a rather common position (e.g.: extending "crocodile ocean yellow" by "submarine" is probably worse than using "air", despite the difference in lengths).