I'd love to understand what you're trying to do, so my questions are:
- I cast the Z ability and the caster is "paused".
I assume you mean "channeling", not "paused", is this correct? (busy casting spell, similar to how blizzard-spell is being cast)
- If then I cast the A ability, the ability is not casted.
So it's not possible to cast A while channel Z, is this correct? It's a totally unrelated spell that have nothing to do with Z and B? (from a casting perspective)
- If then I cast the B ability, the ability is casted.
So you should be able to cast B while channeling Z? How is this supposed to work?
Should you only enable B after channeling Z for at least 0.75 seconds? And casting B cancels hero from channeling?
Or is it:
Start channel Z, if that channels for at least 0.75 seconds, you can cast B (at no extra cost, "finishing the cast" or stoping the hero from channeling), but if you channel for a total of 1.5 seconds, you can cast A instead (finishing the cast in a similar way?)?
Do you need to decide A or B or should it just auto-decide depending on how long you are channeling the Z spell?