When was the "luck!" button added to battles??

i only just noticed this now, after entering a battle and getting confused why it wouldnt let me use my lucky feet even though i was pretty sure i had two (and of course you cant check your hoard while in battle). i did NOT see that new button whatsoever before, but i guess that would explain why ive been hitting "retreat" instead of "rest" so many times lately!

when was that added in? im assuming it uses a lucky foot? i'll have to try next time im actually in a battle worth using one. i looked through the changelogs i could find and didnt see it mentioned anywhere

Yes, it uses a lucky foot if you have one in your hoard! It took me by surprise too- I was wondering why the interface looked different before noticing the option on the far right lol! Was certainly added quite sneakily...