I have been looking all morning for this with no luck. Pretty much like this but slightly different angle, bigger breasts, and I believe a (purple one-eyed?) monster behind her.
I think I last saw it on Sankaku a few years ago, but cant seem to find it. Meanwhile Tits vs Glass Thread
>>6952272
>>6952268
I don't know the exact image, but it sounds like Tentacles and Witches.
I don't think that TvG is actually/d/ but here are some tentacles vs. bewbies.
Oops...forgot link.
http://myanimelist.net/anime/10683/Tentacle_and_Witches
Also:Tentacles vs. Demon chicks
>>6952268