- first strike melee encounters, where a disabling Feat is in play (such as Knockdown).
- first strike arcane encounters, where the first disabling spell to "hit" can matter.
- does not matter for Range attacks.
- does not matter for attacks from stealth.
- must be a disabling-type of attack for it to matter, or the Engine finishes the round no matter what.
If you disengage an encounter, run about, then re-engage, is Initiative rolled again in this Engine? Yes, I can test that out later, but I'm thinking at the moment, not gaming.