I pulled out/turned off the skill "archeotech constructs" and it was blocked.
To unlock it again, I need to perform the achievement again.. 100 times not to die for a techno adept...  (Complete the task 100 times a second time without dying... that's quite a long time..)


A little bit of pre-history.
I haven't played my techno adept for a long time and found that all the talents were erased.
I had to redistribute them all over again.

after a couple of missions
I removed the skill "archeotech constructs" and it stopped being available.

My 3 castellan robots were still available in combat, but I could no longer summon 2 spider packs.