Learn Turkish: Dövme yaptıracakken vazgeçtim. - Just as I was about to get a tattoo, I gave up.

It combines the future tense suffix -acak (about to / will) with the adverbial suffix -ken (while / when). Literally, it means "while being in the state of going to have it done." We use this specific combination to show that an intended action was interrupted or changed at the last minute.

Why isn't there a personal ending on yaptıracakken to show that I was the one about to get it?

The suffix -ken never takes personal endings. We know who was about to get the tattoo because we look at the main verb at the end of the sentence. Since vazgeçtim ends with the first-person marker -m, we know that "I" am the subject for both the interrupted action and the final action.

Why use yaptıracakken instead of just yapacakken?

The -tır part is the causative suffix, which we use when having someone else do something for us. If you said dövme yapacakken, it would mean "just as I was about to give a tattoo" (doing the tattooing yourself on someone else). By using yaptıracakken, it correctly means you were about to have the tattoo done to you by a professional.

I learned that vazgeçmek (to give up) requires the ablative case (-tan / -ten). Why isn't it used here?