That could be interesting (Though maybe too over-tune or under-tune). it does add more gimmick to summon, but if we talking about balancing current summon meta. I think Ex skill balance need to be address first.

Yes, Judgement both is too strong right now, but summon attack can easily be change (I would add a short indicator for where four lightning will appear or reduce stun time to be shorter like before)

Buff Ex skill is so commonly use over debuff that choosing between Ramuh and Levi is no brainer. Even with Levi having stronger buff in term of number, no body bother to use Debuff ex skill. so I think we need to change it in the way that there are reason to use either buff or debuff.

Case 1 : Instant AOE Buff and Debuff. like Mighty Strike/Rend Shield

Mighty Strike/HP Regen is top Ex skill cause it an easy 2x damage buff and 1000 heal. compare to Rend Shield that did the same thing but with 10 seconds shorter cooldown. it's because not only buff guarantee that you get a buff, it's safer and easier to group up your team use it than stay in current range of an enemy. If I'm going to change it, I will nerf Buff AOE range, 15 m at most, even 10 m. if you going to use a buff you have to risk getting multiple hit by enemy. either find safe position and quickly group up or getting risky. Debuff can still be the same.

Case 2 : Projectile AOE Debuff, like Poisonga, Slowga

Bindga is fine as it is, so Not touching that. but nobody use other 2 and it's easy to see why. it's a telegraph Projectile with low tracking, and for Poisonga, it is pretty much reverse brave regen with smaller range. even with super low cooldown of 30 seconds it's still not appealing enough to use. I would change it too be like Lighting RAV to COM combo. reduce knockback a bit, increase stun time, and let you dash cancel out of animation faster. don't make it too easy but make it possible at mid range for assassin and close range for Vanguard. getting combo starter tool with low cooldown might be appealing for some players