My suggestion is as follows:
Option 1: Ignore damage received from using Alter Ego in Story quests;
Option 2: Provide the summoner class with an alternative boost for the duration of the story quests.
During the passage of the Story quest, I found that a record of the received damage is kept in some of them. For this reason, I received a decrease in rank from S to A. On the one hand, this is correct, since these are the conditions of the quest, but on the other hand, it turns out that the summoner class cannot use their strongest skills in order not to receive a decrease in the score.
It is highly illogical that the Summoner class is constrained to do this (as far as I know about other classes).