General answers post.
Is it that, when adding to a spell, larger/more notable addition may be random?
Randomizing additions run under rule "depending how I feel", but you are mostly right; small additions don't usually warrant randomization.
Also are you able to target yourself with a target spell?
As I mentioned before, if spell target is referred simply as "target" then the spell fires visible but ethreal bolt from caster's palm making it essentially aimed spell. So yes, you can aim yourself as long as you can move your hands. But since those golems are pretty strong, some of your cuts are down to bone, severing muscles, tendons and nerves. I'll probaby roll a dice to see if you can target yourself or not.
And that's why it's a good idea to have multiple differently targeted versions of the same spell, because you can be paralysed, blinded, silenced and knocked out.
So, when i was transforming i tried to delete the maximum of words possible (I don't know if there is limit of one word or something per turn to delete stuff)
Deletion/addition/alteration doesn't work on per word basis, but more per section. For example your starter spell could be broken into following sections: <
Pointed target> <
thinks> <
he has only 20 minutes> <
to live>. It could be broken on other ways too, but spell target is one definite section and you can change it quite many ways in one turn. <
thinks> makes major difference how the spell works so it counts as a section. You could add number of conditionals there to determine if spell works as mere illusion or for real. <
he has only 20 minutes> is a section that sets time limit for the spell, though it could be thought as one section with <
thinks> too. And finally <
to live> is another major section of the spell that can be changed in many ways, for example to <
to kill random person>, <
to swim in ceiling>, or <
to live> <
unless he does something>.
So while mutating magic works as traditional Word Morph Game, it's more on functional meta level rather than literally changing a single word at the time. It can sometimes get rather fuzzy and unclear, even for me. Using your latest alteration as example: "<
Looked target> <
thinks> <
he has 20 minutes> <
to live>" --> "<
Looked target> <
thinks>". It looks like you are removing two sections at once, but if you remove only one section the end result doesn't make any sense. "
Looked target thinks he has 20 minutes". 20 minutes what? And "
Looked target thinks to live" doesn't make sense either. So it makes sense to think "
he has 20 minutes to live" as one section to remove in this context because final spell "
Looked target thinks" is sensible spell that grants sapience to inanimate object, or perphaps wakes up sleeping or unconscious person.
I hope this helps instead of confusing people even more.