how is a level 11 skill gem introduced to the drop pool in campaign?

I Have started again in solo self found and have literally bricked my build by going to corrupting warcry without having a level 11 gem. I have been farming temple of Kopec for about 4 hours to get the gem to drop with little to no damage and I have yet to see a skill gem any level. my question is do you need to unlock a lvl 11 skill gem from a quest in act 3 normal or is this just a really bad act of rng..

if anyone has any idea please let me know.