Wow, that is disgustingly bad and a total overkill when the intention was to simply prevent players from summoning on top of the enemy backline. If it releases like this the way to go is to simply reset all those heroes to level 1 and exchange Elena for Jacques, pump everything into him.
I can't imagine how much harder the void challenges will be now.
They simply can't make summon skills this bad. It doesn't come from the backline, it comes from the bloody end of the screen. Virion's swordmen will never reach anything in time. Lilith you need to change the range to be around the hero that casts the skill. Or remove the cooldown from summons, so you are at least able to cast them all as the fight starts, because in that current form you will never want to sacrifice a skill cooldown on a summon skill as they take too long to start making a difference in the battlefield.