Which packs unlock new abilities?

I finally got a ability. I had 2750/6900 items and got the chomp cannon from the 15k. The 15 k packs fill up your items quickly and have a chance to give legendary which the abilities are legendary. The more items you have the more likely you will get more legendary items.

I've been sticking to the 35k packs.

Happy to finally get all the abilities for Foot Soldier, I have all the chomper abilities as well but I'm a much better soldier. I somehow managed to get all the abilities for Scientist but I think that had to do w/the deluxe edition packs.

I think the 1 ability I have out of 600 levels worth of packs came from 35k pack.  I was not aware these were marked as legendary...  Don't recall it being marked that way, but could be wrong.  Anyway, the abilities are FAR too rare.