uhh... FWIW... regarding magic missiles, time travel shield spells and counterspells dancing on the head of an ettin - maybe we are alone in seeing it this way - but the "fiction" of events is based on the final results of what happens - so the fiction behind a magic missile vs shield spell would be "Celeste shielded off the lamia's magic missiles and then..." or for counter spell the "fiction" would be "Celeste countered tha lamia's magic missiles, unravelling the weave of the lamia's inferior magic even as it took shape - enraging the lamia even further." " while the case of magic missile hits would be more like "the lamia conjures three, no four, vicious darts that unerringly struck home and Celeste shuddered with pain."
The intervening steps in the resolution of an action-reaction sequence are not seen as actual fiction until they become final and resolved. In a more cinematic sense - the fiction is what is seen on the screen at the end, not the many different bits and rewrites and improvs and cuts and re-shoots and bloopers and edits (aka the mechanics process) that went into that scene as finally depicted.
thus we avoid some of these serious quandries.