Tina made a mistake not revealing to him that she had to reinforce the target over and over because he is too strong, but this incident is COMPLETELY MC'S FAULT AND NO ONE ELSE.
If i'm literally on my first day of school and my teacher, who just so happens to also be the person who had been training me basically all my life and as such knows my strenght best, and who also just so happens to be a very powerful and renowed magician herself tells me to use 30% of my power I F***ING LISTEN.
Then you add that him not understanding his own OPness is completely ridiculous because EVEN AN ACTUAL 10Y OLD KNOWS BASIC MATH AND CAN CALCULATE 1x10000 (so no, even his INT being fixed doesn't excuse this).
Then you add his non-reaction to coming an inch from outright KILLING WITH HIS OWN HANDS the person closest to him....
This is where i drop it. I like Tina, but a MC with this level of stupidity and absolutely not realistic is an instant out for me.