Starcraft – the range of the mothership core’s “Photon Overcharge”

Question 1 - leaving the Thor's range

It depends on the stage of the ability. The strike cannon ability is actually composed of 3 stages - the preparation stage (switching to deployed mode), the barrage stage (shooting) and the resetting stage (returning to normal mode).

1. If a target leaves the Thor's range during the preparation stage, the Thor will pursue it (if it is able to) and then start the preparation mode again. In that case it behaves as if you just activated the ability beyond its range, and in a similar fashion to other targeted abilities.

2. If the target leaves the Thor's range during the barrage stage, the barrage will immediately stop (inflicting less than maximal damage) and the resetting stage will start. The only ways I know that a target can leave the Thor's range while both it and the Thor are still alive are if

   • the target is an Ultralisk (which are immune to stuns, so they can just walk away)
   • the target is being lifted by a Phoenix
   • the target is being sucked into a vortex
   • the Thor can no longer see the target (e.g. it's behind smoke and a unit providing vision has left, or the target became cloaked by a Mothership and the Thor's player does not have detection there)

Question 2 - Stunning buildings

Yes, the strike cannon "stuns" buildings as well, halting all production and research and disabling the attacks of defensive structures:

You can read more about this ability on this Liquidpedia entry.

This ability is good against almost everything - just use it on every enemy unit as long as you can. Just make sure to prioritize it - meaning, first corrupt the biggest, higher-hp targets, then the medium-hp ones, then the smaller ones and so on.

Why? Because on the one hand, battles usually do not last longer than the cooldown on corruption, so there's no point saving the ability for later. On the other hand, almost always the down-time between battles - or, alternatively, the time it takes the enemy to rebuild his heavy units - is longer than the time it takes the ability to recharge anyway.

Granted, corrupting individual marauders or phoenixes is pretty silly - but as long as you can, and every bigger unit is already corrupted, why not?