I don’t pretend to understand the dynamics of those two spells (Seduction and Spell Lock) but assuming they’re tightly tied to he pet type, this should work.
alt key held - harmable focus unit - cast Seduction at focus unit if Succubus is out
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .cast Spell Lock at focus unit if Felhunter is out
ctrl key held - harmable mouseover unit - cast Seduction at mouseover unit if Succubus is out
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .cast Spell Lock at mouseover unit if Felhunter is out
no alt/ctrl held - harmable target unit - cast Seduction at target unit if Succubus is out
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cast Spell Lock at target unit if Felhunter is out
#showtooltip isn’t really necessary and it can bite you in the butt sometimes because rolling over the action button with #showtooltip shows the spell information while rolling over it with #show shows only the macro name (helps in quickly diagnosing the fairly normal problem of “Ooops, I wrote this nice macro and then forgot to put it on my bars”)
There isn’t any way to determine if the targeted unit is casting or not, by design.
That’s an anti-botting measure put in place by Blizzard.
You can use something like WA to place a “do it now” image over the button that has this macro on it if you feel the need to do so (any non-interactive frame placed over a button has no effect other than as a visual cue).
As to the “control” problem with the macro - that would mean that you have a keybinding conflict with the key bound to the button this macro is placed on.
Rather than remove the control modifier, I’d recommend unbinding the sound toggle in your system keybinding menu. There are a lot of fairly useless things bound that interfere with clean usage of modifiers on keys.
Because [mod:alt] indicates you’re taking action to explicitly cast on your focus and I assume you’d rather not waste the cast and have it hit a random target should be dead.
I’m trying to modify the macro so I won’t need to focus a target before I can cast interrupts, but something is wrong and I can’t cast spells at the arena target 2: