I have already gone over why this rune is a totally bad idea, and even Luke agrees with me! Having zero fear is fucking dangerous and can get someone killed in a battle situation. Yet, Jace once again is stupidly doing it and then dragging Clary into drawing the rune as well.
They only tested it once, and it had mix results to say the least. Actually, Alec was all too ready to out himself and destroy his entire life because of it. We still don’t know if doing this rune will have long-term effects. It’s like taking a medication that hasn’t been fully tested by the by the FDA.
I know they are on the clock, but I can’t help but feel that there is some other way and they are not taking any time to think about this situation logically.