Hi !
Firstly, big thank to all of you who answered.
I'm going to try the Archanarok and Hand of Gork a Mangler, but I doubt it will be sufficient as he almost always screen them with Mortek Guards
If this doesn't work, maybe should I go very cheesy an play like 2x Sporesmasha and Prismatic barrier ? But that's a lot of point just to counter a small part of his army.
I heard about some people blocking LoS with Troggoth units but I don't see how you can do it
Thanks you all !