Meheh Grumpy Stacks x10

I’ve managed to get up to 7 stacks, I don’t have Farideh or Havilar and can’t put him adjacent to 2 tieflings and keep the average 5 seconds on him.

It says 10 or more for the achievement but I can’t see any way to get over 10 in the list? This seems quite impossible for me.

I see someone else’s post which listed more than 10 but they don’t appear in my list? His specialisation doesn’t effect it either :/