Also, @vst-rt16:
Have you played long enough to receive High Khatun from daily login rewards? I used her in the lead position for a long time, although Apoc is probably the better choice because of the 4 hitter A1 and potentially massive heal. Make sure you biuld him with high crit. To trigger the critical heal.
And as a side note, just placing a champion in lead position won't always make them the stun target. The game AI considers several things when choosing the stun target, at least I know this is true against Void CB.
Generally, the CB will stun the target it 'thinks' can kill the fastest.
Ive also noticed that the stun target can change at any time, especially if one of your champions has really low health. Ive noticed the Void CB favors Spirit affinity when choosing tye stun target.
Lastly, the CB AI is blind to buffs like Ally protect, Strengthen, Inc. DEF. Etc., to the point where if he were to use his single attack stun ability, and youve got these buffs up on your stun target, he will still target that champion because the game is just considering the low HP they have, not the buffs probably because they are attributed after the damage is dealt by CB.
Block debuffs does indeed block the stun and the game can't see this either since You can have this buff up on your stun target and the CB still attacking that target. I have also noticed that towards the end of my CB runs, the CB will stun my reviver, who is never the initial stun target to begin with.
There was something going around awhile ago amongst the content creators that you could manipulate which champ the CB selects as stun target by choosing the Steadfast Mastery in Support branch, the theory was that putting this mastery on your champ that you didnt want to get stunned, made the CB less likely to stun them. I have tested this and have had success with this method, but also have had no success at all even with no other changes to my comp and while making several changes to my comp. The most effective change I found in making a champion the stun target is by changing their HP and dDEF in comparison to your other champions' HP and DEF. The CB will see the HP levels of your champions, but appears to be blind from seeing their individual DEF stats as well.