Currently, "OnAbilityPhaseStart" will occur when a spell is cast (before the unit even turns toward the target). "OnSpellStart" will occur after the cast point/animation occurs. I would like an event that triggers immediately after the unit finishes turning toward the target.

There are some ways around this, such as using an immediate frontend spell with no cast point that calls the actual spell, but this introduces other issues (such as casting a hidden ability that has a cast animation).