Because when you ask the question here where you will get a critical analisis of the question you posed, you most likely will not get an answer that will not be supportive of your baises.
The only spell in the opening post that is even simmiler to 'Annihilate' is the 'Summon Shadow Beast' spell. Even then the two spells diverge in concepts to the point that neather can be used as a counter argument basis for arguing against any answer you would of gotten for the OP Q.
I am not going to argue with you. You asked a question and you recived an answer that was based off the text of the spells & rules through critical thinking. If the answers not match your baises, you are free to ignore them in your games.
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If it's not the spell doing the damage, then Annihilate wouldn't operate like a "magic spell attack" or "magic energy attack" as one of the things that split a Zavor?
Answer: That is correct for the A&CD, MI, and A.
However, if you were playing in the PF game the question should of been posed in the PF forum.
Shadow Beasts are inherently magical, so are not a part of the things/beings that do not split a Zavor.
Swords to Snakes is arguably something that would split a Zavor.
May you be blessed with the ability to change course when you are off the mark.
Each question should be give the canon answer 1st, then you can proclaim your house rules.
Reading and writing (literacy) is how people on BBS interact.