if anyone spent time reading the eudemons forums they would of read gm Manitou say that luck hasnt been implemented yet and it only gives your pets extra points for stars so far.
I have however noticed i had a signifigantly easier time getting yellows to work on my higher lvl character (who coinsidentally has hi luck pet) and a hard tiem getting yellows to work on my noob mage.
as far as a trick to getting gears + 12 is conserned however try this...bring atleast 20 yellows with you. You will notice after you use a yellow the bonus window stays open, keep going until you get + 12 without closing the bonus window. this seems to make a world of difference, or atleast i had no troubles getting + 6 and + 7 with normal yellows (super yellow to + 9) followed by no troubles reaching + 12
no troubles reaching + 12 isnt 100% accurate, boots and helmet seem to be more difficult than other gears. boots and helmet consider bringing minimum of 30 yellows, might take a couple tries but you can get it.
people sell yellows for like 400k so if you run logbot overnight then you got 20-40mil to buy yellows with.