GOT STUCK! Can you give me an opinion on such a tagline for a vocabulary building app?

It's okay, this is normal, we are human beings after all. Take a break and try some other time. Anyhow, I assume it's a speech game? so here are my initial thoughts:

Speak to find more diamonds (or gold/gems).
Say more and become rich.

Mentioning "rich" and "diamonds" may attract more audience as well.

tbh I ain't too sure a miner gal gonna resonate with too many people -- speshly if she be the persona powerin' up the vocab.

Gotta figure how this might work out in practice.

So let's assoom we got vocab-deprived SAM, an' let's say he wants in on more killer words he can throw around meaningfully an' productively.

Likely he gonna stroll up to Miner Gal (after descendin' into her deep an' dark underground vestibule) an' say sumthin' like, "hey, where can I get a DICTIONARY?"

That is when Miner Gal hands Sam a shovel, an' says GO DIG!

An' then Sam replies, "just give me the book already. I can look in on a random number generating website, and pick out words at random, page by page, reference by reference, and discover cool stuff like a GARFANGLE is a funky kind of spear."

What happens next kinda depends on whether Miner Gal is touchy.

If'n she okay with constructive criticism, likely she gonna hop herself outta the mine an' switch out the all-body carbonized look for mebbe mascara an' look in also on moisturizin' skincare products stop her palms an' fingertips feelin' like she a professional triceratops masseuse.

If'n she not okay with constructive criticism, likely she gonna wave a dead canary around an' tantrum out.

Anyways, your problem here is Miner Gal.

What your app needs is a signature character who plucks words outta the air -- a far easier proposition than diggin' stuff up with a pickaxe, an' far more in toon with the element presides over matters communicatorial.